#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) { return a % b == 0 ? b : gcd(b, a % b); }
int sod(int n, int b) {
  int sum = 0;
  while ((n / b) != 0) {
    sum = sum + (n % b);
    n = n / b;
  }
  return sum + (n % b);
}
int main() {
  int n, tb;
  cin >> n;
  int i, sum = 0;
  for (i = 2; i < n; i++) {
    sum += sod(n, i);
  }
  tb = n - 2;
  int num, den;
  num = sum / gcd(sum, tb);
  den = tb / gcd(sum, tb);
  cout << num << "/" << den << endl;
  return 0;
}
