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