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