#include <bits/stdc++.h>
using namespace std;
long long int i, j = 0, k, l, m1, m2, m3, m4, m, n, a[100001];
int main() {
  cin >> n;
  m = 0;
  for (i = 2; i < n; i++) {
    m1 = n;
    while (m1 != 0) {
      m += m1 % i;
      m1 /= i;
    }
  }
  n = n - 2;
  for (i = n; i >= 2; i--) {
    if (n % i == 0 && m % i == 0) {
      n = n / i;
      m = m / i;
      break;
    }
  }
  cout << m << "/" << n;
}
