#include <bits/stdc++.h>
using namespace std;
int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); }
int main() {
  long x, y = 0;
  cin >> x;
  int i = 2;
  while (i < x) {
    int j = x;
    while (j > 0) {
      y += j % i;
      j /= i;
    }
    i++;
  }
  x -= 2;
  int mod = GCD(y, x);
  cout << y / mod << "/" << x / mod << endl;
  cin >> x;
  return 0;
}
