#include <bits/stdc++.h>
using namespace std;
int changeBase(int number, int base) {
  int sum = 0;
  while (number > 0) {
    sum += number % base;
    number /= base;
  }
  return sum;
}
int gcd(int num1, int num2) {
  return num2 == 0 ? num1 : gcd(num2, num1 % num2);
}
int main() {
  int number, counter = 0, sum = 0;
  cin >> number;
  for (int i = 2; i < number; i++) {
    counter++;
    sum += changeBase(number, i);
  }
  int GCD = gcd(sum, counter);
  cout << sum / GCD << "/" << counter / GCD;
  return 0;
}
