#include <iostream>
#include <fstream>
using namespace std;

int fives(int x) {
  int count = 0;
  while (x > 0) {
    if (x % 5 == 0) { 
      count++;
      x /= 5;
    } else {
      x = 0;
    }
  }
  return count;
}

int main()
{
  ifstream input("fact.in");
  int p;
  input >> p;

  int count = 0;
  int result = 0;
  while (count < p) {
    result += 5;
    count += fives(result);
  }
  if (result == 0) { result = 1; }

  ofstream output("fact.out");
  output << result;
}