#include <bits/stdc++.h>
using namespace std;
long long int g(long long int a, long long int b) {
  if (a == b) {
    return a;
  } else if (a == 1 || b == 1) {
    return 1;
  } else if (a > b) {
    return g(a - b, b);
  } else if (b > a) {
    return g(b - a, a);
  }
}
int main() {
  long long int n, i, j, k = 0, p = 0;
  cin >> n;
  for (i = 2; i < n; i++) {
    long long int q = n;
    while (q > 0) {
      p = p + q % i;
      q = q / i;
    }
  }
  k = n - 2;
  long long int x = g(p, k);
  p = p / x;
  k = k / x;
  cout << p << "/" << k;
  return 0;
}
