#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  while (b) {
    int t = a % b;
    a = b;
    b = t;
  }
  return a;
}
int main() {
  int n;
  scanf("%d", &n);
  int ans = 0;
  for (int i = 2; i < n; i++) {
    int t = n;
    while (t) {
      ans += t % i;
      t /= i;
    }
  }
  int d = gcd(ans, n - 2);
  printf("%d/%d\n", ans / d, (n - 2) / d);
  return 0;
}
