#include <bits/stdc++.h>
using namespace std;
int getAC(int num, int pos) {
  int sum = 0;
  while (num != 0) {
    sum += num % pos;
    num /= pos;
  }
  return sum;
}
int gcd(int a, int b) { return ((!b) ? a : gcd(b, a % b)); }
int main() {
  int num;
  int digits = 0;
  cin >> num;
  for (int i = 2; i < num; i++) digits += getAC(num, i);
  int g = gcd(digits, num - 2);
  cout << digits / g << "/" << (num - 2) / g << endl;
  return 0;
}
