#include <bits/stdc++.h>
using namespace std;
int hc(int a, int b) {
  if (b == 0) return a;
  return hc(b, a % b);
}
int main() {
  int n, a[10010], i, sum = 0;
  cin >> n;
  int k = n;
  for (i = 2; i < n; i++) {
    a[i] = i;
  }
  for (i = 2; i < n; i++) {
    while (n != 0) {
      sum = sum + n % a[i];
      n = n / a[i];
    }
    n = k;
  }
  int q = k - 2;
  int h = hc(sum, k - 2), b;
  sum = sum / h;
  b = q / h;
  cout << sum << "/" << b << endl;
}
