#include <bits/stdc++.h>
using namespace std;
int n, s, x, ans, sb;
int main() {
  cin >> n;
  for (int i = 2; i < n; i++) {
    x = n;
    while (x) {
      s += x % i;
      x /= i;
    }
  }
  sb = n - 2;
  for (int i = 2; i <= min(s, sb); i++) {
    while (s % i == 0 && sb % i == 0) {
      s /= i;
      sb /= i;
    }
  }
  cout << s << "/" << sb;
  return 0;
}
