#include <bits/stdc++.h>
using namespace std;
int sum;
inline int conversion(int n, int i) {
  while (1) {
    int x = n / i;
    sum += (n - (i * x));
    n = x;
    if (n == 0) break;
  }
  return 1;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  for (int i = 2; i < n; ++i) {
    conversion(n, i);
  }
  int numerator = sum, denominator = n - 2;
  for (int x = 2; x <= 1000; ++x) {
    if (numerator % x == 0 && denominator % x == 0) {
      numerator /= x;
      denominator /= x;
      x = 1;
    }
  }
  cout << numerator << "/" << denominator << "\n";
  return 0;
}
