#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (!b)
    return a;
  else
    return gcd(b, a % b);
}
int main() {
  int a, i, sum;
  cin >> a;
  sum = 0;
  for (i = 2; i < a; i++) {
    int tmp = a;
    while (tmp > 0) {
      sum += tmp % i;
      tmp /= i;
    }
  }
  int m;
  m = gcd(sum, a - 2);
  cout << sum / m << "/" << (a - 2) / m << endl;
  return 0;
}
