#include <fstream.h>


ifstream f("fact.in");
ofstream g("fact.out");

long v[1000]={0,0,200000,400000,600000,800000,1000000,1200000,1400000,1600000,1800000,2000000,2200000,2400000,2600000,2800000,3000000,3200000,3400000,3600000,3800000,4000000,4200000,4400000,4600000,4800000,5000000,5200000,5400000,5600000,5800000,6000000,6200000,6400000,6600000,6800000,7000000,7200000,7400000,7600000,7800000,8000000,8200000,8400000,8600000,8800000,9000000,9200000,9400000,9600000,9800000,10000000,10200000,10400000,10600000,10800000,11000000,11200000,11400000,11600000,11800000,12000000,12200000,12400000,12600000,12800000,13000000,13200000,13400000,13600000,13800000,14000000,14200000,14400000,14600000,14800000,15000000,15200000,15400000,15600000,15800000,16000000,16200000,16400000,16600000,16800000,17000000,17200000,17400000,17600000,17800000,18000000,18200000,18400000,18600000,18800000,19000000,19200000,19400000,19600000,19800000,20000000,20200000,20400000,20600000,20800000,21000000,21200000,21400000,21600000,21800000,22000000,22200000,22400000,22600000,22800000,23000000,23200000,23400000,23600000,23800000,24000000,24200000,24400000,24600000,24800000,25000000,25200000,25400000,25600000,25800000,26000000,26200000,26400000,26600000,26800000,27000000,27200000,27400000,27600000,27800000,28000000,28200000,28400000,28600000,28800000,29000000,29200000,29400000,29600000,29800000,30000000,30200000,30400000,30600000,30800000,31000000,31200000,31400000,31600000,31800000,32000000,32200000,32400000,32600000,32800000,33000000,33200000,33400000,33600000,33800000,34000000,34200000,34400000,34600000,34800000,35000000,35200000,35400000,35600000,35800000,36000000,36200000,36400000,36600000,36800000,37000000,37200000,37400000,37600000,37800000,38000000,38200000,38400000,38600000,38800000,39000000,39200000,39400000,39600000,39800000,40000000,40200000,40400000,40600000,40800000,41000000,41200000,41400000,41600000,41800000,42000000,42200000,42400000,42600000,42800000,43000000,43200000,43400000,43600000,43800000,44000000,44200000,44400000,44600000,44800000,45000000,45200000,45400000,45600000,45800000,46000000,46200000,46400000,46600000,46800000,47000000,47200000,47400000,47600000,47800000,48000000,48200000,48400000,48600000,48800000,49000000,49200000,49400000,49600000,49800000,50000000,50200000,50400000,50600000,50800000,51000000,51200000,51400000,51600000,51800000,52000000,52200000,52400000,52600000,52800000,53000000,53200000,53400000,53600000,53800000,54000000,54200000,54400000,54600000,54800000,55000000,55200000,55400000,55600000,55800000,56000000,56200000,56400000,56600000,56800000,57000000,57200000,57400000,57600000,57800000,58000000,58200000,58400000,58600000,58800000,59000000,59200000,59400000,59600000,59800000,60000000,60200000,60400000,60600000,60800000,61000000,61200000,61400000,61600000,61800000,62000000,62200000,62400000,62600000,62800000,63000000,63200000,63400000,63600000,63800000,64000000,64200000,64400000,64600000,64800000,65000000,65200000,65400000,65600000,65800000,66000000,66200000,66400000,66600000,66800000,67000000,67200000,67400000,67600000,67800000,68000000,68200000,68400000,68600000,68800000,69000000,69200000,69400000,69600000,69800000,70000000,70200000,70400000,70600000,70800000,71000000,71200000,71400000,71600000,71800000,72000000,72200000,72400000,72600000,72800000,73000000,73200000,73400000,73600000,73800000,74000000,74200000,74400000,74600000,74800000,75000000,75200000,75400000,75600000,75800000,76000000,76200000,76400000,76600000,76800000,77000000,77200000,77400000,77600000,77800000,78000000,78200000,78400000,78600000,78800000,79000000,79200000,79400000,79600000,79800000,80000000,80200000,80400000,80600000,80800000,81000000,81200000,81400000,81600000,81800000,82000000,82200000,82400000,82600000,82800000,83000000,83200000,83400000,83600000,83800000,84000000,84200000,84400000,84600000,84800000,85000000,85200000,85400000,85600000,85800000,86000000,86200000,86400000,86600000,86800000,87000000,87200000,87400000,87600000,87800000,88000000,88200000,88400000,88600000,88800000,89000000,89200000,89400000,89600000,89800000,90000000,90200000,90400000,90600000,90800000,91000000,91200000,91400000,91600000,91800000,92000000,92200000,92400000,92600000,92800000,93000000,93200000,93400000,93600000,93800000,94000000,94200000,94400000,94600000,94800000,95000000,95200000,95400000,95600000,95800000,96000000,96200000,96400000,96600000,96800000,97000000,97200000,97400000,97600000,97800000,98000000,98200000,98400000,98600000,98800000,99000000,99200000,99400000,99600000,99800000,100000000};
long z[1000]={0,0,49998,100004,150008,200014,250018,300024,350028,400034,450039,500045,550050,600055,650060,700065,750070,800075,850080,900086,950090,1000097,1050101,1100107,1150111,1200117,1250122,1300128,1350133,1400138,1450143,1500149,1550154,1600159,1650164,1700170,1750174,1800180,1850184,1900190,1950194,2000201,2050205,2100211,2150217,2200221,2250227,2300231,2350237,2400241,2450249,2500254,2550260,2600265,2650270,2700275,2750280,2800285,2850290,2900295,2950302,3000306,3050312,3100316,3150322,3200326,3250332,3300336,3350342,3400347,3450353,3500358,3550363,3600368,3650373,3700378,3750384,3800389,3850395,3900399,3950406,4000410,4050416,4100420,4150426,4200432,4250436,4300442,4350446,4400453,4450457,4500463,4550467,4600473,4650478,4700483,4750488,4800493,4850498,4900505,4950510,5000516,5050521,5100527,5150531,5200537,5250541,5300547,5350551,5400558,5450563,5500568,5550573,5600578,5650583,5700588,5750593,5800598,5850603,5900610,5950614,6000620,6050624,6100630,6150634,6200640,6250646,6300652,6350659,6400663,6450669,6500673,6550679,6600683,6650689,6700694,6750699,6800704,6850710,6900715,6950720,7000725,7050730,7100735,7150741,7200745,7250751,7300755,7350763,7400767,7450773,7500778,7550784,7600789,7650794,7700799,7750804,7800809,7850815,7900820,7950826,8000830,8050836,8100840,8150846,8200850,8250856,8300860,8350867,8400873,8450877,8500883,8550887,8600893,8650897,8700903,8750908,8800915,8850920,8900925,8950930,9000935,9050940,9100945,9150950,9200956,9250960,9300967,9350971,9400977,9450981,9500987,9550991,9600997,9651002,9701007,9751012,9801019,9851024,9901029,9951034,10001040,10051045,10101051,10151055,10201061,10251065,10301072,10351076,10401082,10451088,10501092,10551098,10601102,10651108,10701112,10751119,10801123,10851129,10901134,10951139,11001144,11051149,11101154,11151159,11201164,11251171,11301176,11351182,11401186,11451192,11501196,11551202,11601206,11651212,11701217,11751223,11801228,11851233,11901238,11951243,12001248,12051253,12101258,12151264,12201268,12251277,12301281,12351287,12401291,12451297,12501303,12551309,12601315,12651319,12701326,12751330,12801336,12851340,12901346,12951351,13001356,13051361,13101366,13151371,13201377,13251382,13301387,13351392,13401398,13451402,13501408,13551412,13601418,13651422,13701429,13751434,13801440,13851445,13901450,13951455,14001460,14051465,14101470,14151475,14201482,14251486,14301492,14351496,14401502,14451506,14501512,14551516,14601522,14651530,14701534,14751540,14801544,14851550,14901554,14951560,15001565,15051571,15101576,15151582,15201587,15251592,15301597,15351602,15401607,15451613,15501617,15551623,15601627,15651634,15701638,15751644,15801648,15851654,15901659,15951664,16001669,16051674,16101679,16151685,16201690,16251696,16301701,16351707,16401711,16451717,16501721,16551727,16601731,16651738,16701744,16751748,16801754,16851758,16901764,16951768,17001774,17051778,17101786,17151791,17201796,17251801,17301806,17351811,17401816,17451821,17501827,17551832,17601839,17651843,17701849,17751853,17801859,17851863,17901869,17951874,18001879,18051884,18101890,18151895,18201900,18251905,18301910,18351915,18401921,18451925,18501931,18551935,18601942,18651946,18701952,18751958,18801964,18851970,18901974,18951980,19001984,19051991,19101995,19152001,19202006,19252011,19302016,19352021,19402026,19452031,19502036,19552043,19602048,19652054,19702058,19752064,19802068,19852074,19902078,19952084,20002089,20052096,20102101,20152106,20202111,20252116,20302121,20352126,20402131,20452137,20502141,20552148,20602152,20652158,20702162,20752168,20802172,20852178,20902184,20952188,21002195,21052199,21102205,21152209,21202215,21252220,21302226,21352231,21402236,21452241,21502247,21552252,21602257,21652262,21702268,21752272,21802278,21852282,21902288,21952292,22002300,22052304,22102310,22152315,22202320,22252325,22302330,22352335,22402340,22452345,22502352,22552357,22602363,22652367,22702373,22752377,22802383,22852387,22902393,22952400,23002404,23052410,23102414,23152420,23202424,23252430,23302434,23352440,23402445,23452451,23502456,23552461,23602466,23652471,23702476,23752482,23802487,23852493,23902497,23952504,24002508,24052514,24102518,24152524,24202529,24252534,24302539,24352544,24402549,24452557,24502562,24552567,24602572,24652578,24702582,24752588,24802592,24852598,24902602,24952609,25002615};

long nr0(long a)
{
    long nr=0;
    if (a==0)
      return 0;
    else
    {
    long b;
        b=a;
        while (b%5==0)
          {
              nr++;
              b=b/5;
          }
      return nr;
}
}
    

int main()
{
    long p;
    f>>p;
    if (p==0)
      g<<1;
    else
    {
    long i;
    i=1;
    while (z[i]<p)
      i++;  
    i--;
    long j;
    long nrc=z[i]-nr0(v[i]);
    int sw=0;
    for (j=v[i];j<=v[i+1] && sw==0;j++)
      {
         if (p==nrc)
           {
           g<<j-1;
           sw=1;
           }
         nrc=nrc+nr0(j);
         
      }
    if (sw==0)
      g<<"-1"; 
       }      
     
     }