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