#include <bits/stdc++.h>
using namespace std;
int gcd(int x, int y) {
  if (y < 0 || y > 0)
    return gcd(y, x % y);
  else
    return x;
}
int main() {
  int n;
  cin >> n;
  int ans = 0;
  for (int i = 2; i <= n - 1; i++) {
    int x = n;
    while (x >= i) {
      ans = ans + x % i;
      x = x / i;
    }
    ans = ans + x;
  }
  cout << ans / gcd(ans, n - 2) << "/" << (n - 2) / gcd(ans, n - 2);
  return 0;
}
