#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  int smaller = min(a, b);
  int bigger = max(a, b);
  for (int i = smaller;; i--)
    if (smaller % i == 0 && bigger % i == 0) return i;
}
int main() {
  int a, s = 0;
  cin >> a;
  for (int x = 2; x < a; x++) {
    for (int i = a; i > 0; i /= x) s += i % x;
  }
  int dvd = gcd(s, a - 2);
  cout << s / dvd << "/" << (a - 2) / dvd;
  return 0;
}
