#include <bits/stdc++.h>
using namespace std;
int gcd(int x, int y) {
  int r;
  for (; y != 0;) {
    r = x % y;
    x = y;
    y = r;
  }
  return x;
}
int Sum(int x, int k) {
  int ans = 0;
  while (x) {
    ans += x % k;
    x /= k;
  }
  return ans;
}
int a = 0;
int main() {
  int n;
  cin >> n;
  for (int i = 2; i < n; i++) {
    a += Sum(n, i);
  }
  int b = n - 2;
  int c = gcd(a, b);
  a /= c, b /= c;
  cout << a << "/" << b << endl;
}
