#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (a == 0) return b;
  if (b == 0) return a;
  if (a == b) return a;
  if (a > b) return gcd(a - b, b);
  return gcd(a, b - a);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t = 1;
  while (t--) {
    int a, h, sum = 0;
    cin >> a;
    for (int i = 2; i < a; i++) {
      int n = a;
      while (n >= i) {
        sum += n % i;
        n = n / i;
      }
      sum += n;
    }
    h = gcd(sum, a - 2);
    cout << sum / h << "/" << (a - 2) / h << endl;
  }
  return 0;
}
