#include <bits/stdc++.h>
using namespace std;
int basecon(int n, int b);
int gcd(int a, int b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
int basecon(int n, int b) {
  int sum = 0;
  while (n) {
    sum = sum + (n % b);
    n = n / b;
  }
  return sum;
}
int main() {
  int n, sum = 0, y, g;
  cin >> n;
  y = n - 2;
  for (int i = 2; i < n; ++i) {
    sum = sum + basecon(n, i);
  }
  g = gcd(sum, y);
  sum = sum / g;
  y = y / g;
  cout << sum << "/" << y << endl;
}
