#include <iostream>
#include <fstream>

using namespace std;
int puteremax(int n){
    int s=1;
while(s<=n){
    s=5*s;
   }
 return  s/5;}

int main()
{   ifstream in("fact.in");
   ofstream out("fact.out");
   int k;
   in>>k;
   int i;
   i=4*k;
   if(k==0) out<<"1";
   int ok=1;
   while(k>0&&i<=5*k&&ok==1){
    int x=puteremax(i);
    int s=0;
    while(x>1){
            s=s+i/x;
    x=x/5;

    }
    if(s==k){

    ok=0;
    out<<i;}
    else i++;
   }
   if(ok==1&&k>0) out<<"-1";

   return 0;}