#include <bits/stdc++.h>
int ans = 0, a, b, x;
int p(int n, int x) {
  int q = 0;
  while (n) {
    q += n % x;
    n /= x;
  }
  return q;
}
int main() {
  scanf("%d", &x);
  for (int i = 2; i < x; i++) ans += p(x, i);
  a = x - 2;
  b = ans;
  while (a && b)
    if (a > b)
      a %= b;
    else
      b %= a;
  printf("%d/%d", ans / (a + b), (x - 2) / (a + b));
  return 0;
}
