#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-9;
long long gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
int main() {
  long long t, w, b;
  cin >> t >> w >> b;
  long long tmp = gcd(w, b);
  long long ans = min(min(w - 1, b - 1), t);
  if (!(1. * w / tmp * b - t > eps)) {
    long long lcm = w / tmp * b;
    ans += t / lcm + (t / lcm - 1) * min(w - 1, b - 1) +
           min(min(w - 1, b - 1), t % lcm);
  }
  long long now = gcd(ans, t);
  cout << ans / now << "/" << t / now << endl;
  return 0;
}
