#include <bits/stdc++.h>
using namespace std;
long gcd(long a, long b) { return b == 0 ? a : gcd(b, a % b); }
int main() {
  long p, i, n, a, sum = 0;
  cin >> a;
  for (i = 2; i <= a - 1; i++) {
    n = a;
    while (n > 0) {
      sum += n % i;
      n = n / i;
    }
  }
  p = gcd(sum, a - 2);
  cout << sum / p << '/' << (a - 2) / p << endl;
  return 0;
}
