#include <bits/stdc++.h>
using namespace std;
int s, a, b, n, d;
int g(int a, int b) { return b ? g(b, a % b) : a; }
int main() {
  cin >> a;
  n = a - 2;
  for (int i = 2; i < a; i++) {
    b = a;
    while (b) {
      s += b % i;
      b /= i;
    }
  }
  d = g(s, n);
  cout << s / d << "/" << n / d;
  return 0;
}
