#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  while (b) b ^= a ^= b ^= a %= b;
  return a;
}
int doMagic(int a, int p) {
  int res = 0;
  while (a >= p) {
    res += a % p;
    a /= p;
  }
  return res + a;
}
int main() {
  int A;
  cin >> A;
  int res = 0;
  for (int i = 2; i <= A - 1; i++) res += doMagic(A, i);
  int GCD = gcd(res, (A - 1) - 2 + 1);
  cout << res / GCD << '/' << ((A - 1) - 2 + 1) / GCD;
  return 0;
}
