#include <bits/stdc++.h>
using namespace std;
const long double pi = 3.1415926535897932384626433832795;
const long double eps = 1e-9;
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int chck(int a, int b) {
  int sum = 0;
  while (a) {
    sum += a % b;
    a = a / b;
  }
  return sum;
}
int main() {
  int a, i;
  cin >> a;
  int num = 0, den = a - 2;
  for (i = 2; i < a; i++) {
    num = num + chck(a, i);
  }
  int x = gcd(num, den);
  num = num / x;
  den = den / x;
  cout << num << "/" << den << endl;
  return 0;
}
