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