#include <bits/stdc++.h>
using namespace std;
int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); }
int ok(int i, int n) {
  int m = 0;
  while (n > 0) {
    m += n % i;
    n = n / i;
  }
  return m;
}
int main() {
  int n;
  cin >> n;
  int sum = 0;
  int cnt = 0;
  for (int i = 2; i < n; i++) {
    sum += ok(i, n);
    cnt++;
  }
  int mod = GCD(sum, cnt);
  cout << sum / mod << "/" << cnt / mod;
  return 0;
}
