#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (!b) return a;
  return gcd(b, a % b);
}
int main() {
  int a, t, j, s1, k;
  scanf("%d", &a);
  for (j = 2, s1 = 0; j < a; ++j) {
    k = a;
    while (k) {
      s1 += k % j;
      k /= j;
    }
  }
  k = gcd(s1, a - 2);
  printf("%d/%d\n", s1 / k, (a - 2) / k);
  return 0;
}
