#include <fstream>
using namespace std;
long long p,nrz,i;
long long dr=100000000,st,n,c;
ofstream g("fact.out");
long long nrzero( long long cif )
{
     long t = 0;
     while( cif )
     {
            t += cif/5;
            cif /= 5;
     }
     return t;
}

 long long cautare(long long a, long long b)
{
st=0;
dr=1000000000LL;
n=1;
if(p>0){
while(n){     c=(st+dr)/2;
              nrz=nrzero(c);
              if(nrz==p&&st==dr) {n=st;break;} 
              if(dr<st) {n=-1;break;} 
    	      if(p>nrz) st=c+1;
   	  	      else dr=c-1;                            
           }
           
}   
return n;
}
int main()
{
        ifstream f("fact.in");
        f>>p;   
       i=cautare(st,dr);
       g<<i;
        return 0;}