#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
int main() {
  int A;
  scanf("%d", &A);
  int u = 0, d = A - 2;
  for (int i = 2; i <= A - 1; i++) {
    int t = A;
    while (t) {
      u += t % i;
      t /= i;
    }
  }
  int g = gcd(u, d);
  printf("%d/%d", u / g, d / g);
  return 0;
}
