#include <bits/stdc++.h>
using namespace std;
int gcd(int x, int y) {
  if (x < y) swap(x, y);
  return y == 0 ? x : gcd(y, x % y);
}
int main() {
  int n, sum = 0;
  scanf("%d", &n);
  for (int i = 2; i < n; i++) {
    int x = n;
    while (x) {
      sum += x % i;
      x /= i;
    }
  }
  n -= 2;
  int g = gcd(sum, n);
  printf("%d/%d\n", sum / g, n / g);
  return 0;
}
