#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (a == b)
    return a;
  else if (a % 2 == 0 and b % 2 == 0)
    return 2 * gcd(a / 2, b / 2);
  else if (a % 2 == 0)
    return gcd(a / 2, b);
  else if (b % 2 == 0)
    return gcd(a, b / 2);
  else
    return gcd((abs(a - b) / 2), (min(a, b)));
}
int main() {
  int n, a = 0;
  cin >> n;
  for (int i = 2; i < n; ++i) {
    int t = n;
    while (t > 0) {
      a += t % i;
      t = t / i;
    }
  }
  int c = gcd(a, n - 2);
  cout << a / c << "/" << (n - 2) / c << endl;
}
