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