#include <iostream>
#include <fstream>
#include <cmath>
using namespace std;
int main()
{
  int p, n, b, i;
  ifstream f("fact.in");
  ofstream g("fact.out");
  f >> p;
  n = 5 * p;
  b = 1;
  if (n < 25) g << n;
  while (n > 25 * b )
    if ((n - 5 * b) >= 25 * b) {
      n -= 5 * b;
      b++;
    }
  if (n > 25 * b) g << -1;
  else g << n;
  f.close ();
  g.close ();
  return 0;
}