#include <bits/stdc++.h>
using namespace std;
int a[1100];
int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
int main() {
  int n, i, j, tmp, cnt = 0, sum = 0;
  memset(a, 0, sizeof(a));
  scanf("%d", &n);
  for (i = 2; i < n; i++) {
    tmp = n;
    while (tmp) {
      a[cnt] += tmp % i;
      tmp /= i;
    }
    cnt++;
  }
  for (i = 0; i < cnt; i++) sum += a[i];
  printf("%d/%d\n", sum / gcd(sum, n - 2), (n - 2) / gcd(sum, n - 2));
  return 0;
}
