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