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