#include <iostream>
#include <fstream>
using namespace std;
 
int fives(int x) {
  int count = 0;
  while ((x > 0) && (x % 5 == 0)) {
    count++;
    x /= 5;
  }
  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 (count > p) { result == -1; }
  if (result == 0) { result == 1; }
 
  ofstream output("fact.out");
  output << result;
}