#include <bits/stdc++.h>
using namespace std;
int hcf(int a, int b) {
  int r = 0;
  while (b != 0) {
    r = a % b;
    a = b;
    b = r;
  }
  return (a);
}
int main() {
  int n;
  while (scanf("%d", &n) != EOF) {
    int sum = 0;
    for (int i = 2; i <= n - 1; i++) {
      int m = n;
      while (m / i != 0) {
        sum += m % i;
        m = m / i;
      }
      sum += m;
    }
    cout << sum / hcf(sum, n - 2) << "/" << (n - 2) / hcf(sum, n - 2) << endl;
  }
  return 0;
}
