#include <bits/stdc++.h>
using namespace std;
int a;
bool read() {
  if (!(cin >> a)) return false;
  return true;
}
int calc(int x) {
  int v = a;
  int res = 0;
  while (v) {
    res += (v % x);
    v /= x;
  }
  return res;
}
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
void solve() {
  int en = 0, den = a - 2;
  for (int i = 0; i < int(a); ++i)
    if (i >= 2) en += calc(i);
  int g = gcd(en, den);
  en /= g;
  den /= g;
  cout << en << "/" << den << endl;
}
int main() {
  while (read()) solve();
  return 0;
}
