#include <iostream>
#include <fstream>
using namespace std;
int main()
{   ifstream fin ("fact.in");
    ofstream fout ("fact.out");
  int P , N;
  long long st , dr ,  m, put; 
    st=1;
    dr=100000000 ;
  fin>>P ;
 while(st<=dr)
 {  put=5;
   m=(st+dr)/2 ;
   N=0;
  while(m/put)
   { N+=m/put ;
     put*=5;
    }
 if(N==P) 
 {  if(m-m%5==0)
  fout<<"1"; 
  else 
  fout<<m-m%5; 
  dr=-1;
 }
 else 
 if (N>P)
 dr=m-1 ;
 else 
  st=m+1 ;
 }
 if(dr!=-1) 
 fout<< "-1";
 return 0;
 }