#include <bits/stdc++.h>
using namespace std;
int main() {
  int sum = 0, n, mod;
  cin >> n;
  int x = n;
  for (int i = 2; i < x; i++) {
    n = x;
    while (n > i || n == i) {
      mod = n % i;
      n /= i;
      sum += mod;
    }
    mod = n % i;
    sum += mod;
  }
  int k = sum, kk = x - 2, temp;
  while (k % kk != 0) {
    temp = k;
    k = kk;
    kk = temp % k;
  }
  cout << sum / kk << "/" << (x - 2) / kk;
}
