#include <bits/stdc++.h>
using namespace std;
const double EPS = 1e-8;
int sun(int a, int b) {
  int s = 0;
  while (a) {
    s += a % b;
    a /= b;
  }
  return s;
}
long long sum;
long long A;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
int main() {
  while (cin >> A) {
    sum = 0;
    int b;
    long long X, Y;
    Y = A - 2;
    X = 0;
    for (b = 2; b < A; ++b) {
      X += sun(A, b);
    }
    long long c = gcd(X, Y);
    X /= c;
    Y /= c;
    cout << X << '/' << Y << endl;
  }
  return 0;
}
