#include <stdio.h>
#include <iostream>
using namespace std;

long P,N,tmp,zeros;
int main()
{
  freopen("fact.in","r",stdin);
  freopen("fact.out","w",stdout);
  cin >> P;
  if (P==0) cout << "1";
  else
    {
      // se arata usor ca daca N! are cel putin N zerouri, atunci N>= 4P
      tmp=N=4*P;
      while (tmp/5 > 0)
	{ tmp=tmp/5; zeros+=tmp;}
      while (zeros < P)
	if ((++N)%5==0)
	  {
	    ++zeros; tmp=N/5;
	    while (tmp%5 ==0)
	      {
		++zeros; tmp/=5;
	      }
	  }
      if (zeros > P) cout << "-1";
      else cout << N;
    }
  return 0;
}