#include <iostream>
#include <fstream>
#include <cmath>

using namespace std;

unsigned long long int factorial(int P);

int main()
{
  ifstream f("fact.in");
  ofstream g("fact.out");
  int P;
  f >> P;
  P=pow(10,P);
  int n=1;
  while(factorial(n) % P)
    n++;
  cout << n;
  return 0;
}

unsigned long long int factorial(int P)
{
  if(P == 1)
    return 1;
  else
    return P * factorial(P-1);
}