#include <iostream>
#include<fstream>
#include<math.h>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");

int main()
{
int n,p,s,i;
i=1;
n=1;
in>>p;
while(s%(pow(10,p)!=0))
      {
          s=s*i;
          i=i+1;
          n=i;
      }
      out<<n;

    return 0;
}