#include <bits/stdc++.h>
char c[5] = "ROYG";
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  int n, i;
  scanf("%d", &n);
  int ans = 0;
  for (i = 2; i < n; i++) {
    int u = n;
    while (u) {
      ans += u % i;
      u /= i;
    }
  }
  int uu = gcd(ans, n - 2);
  printf("%d/%d\n", ans / uu, (n - 2) / uu);
  return 0;
}
