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