#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
int main() {
  ios_base::sync_with_stdio(false);
  long long t, w, b;
  cin >> t >> w >> b;
  long long g = gcd(w, b);
  long double t1 = w / g, t2 = b;
  long long lcm = t1 * t2 < 1e19 ? (w / g) * b : 5 * (1ll << 60);
  long long x = (t / lcm + 1);
  long long p =
      (t / lcm + 1) * min(w, b) - 1 - max(min(w, b) - 1 - t % lcm, 0ll);
  cout << p / gcd(p, t) << "/" << t / gcd(p, t) << endl;
}
