#include <bits/stdc++.h>
using namespace std;
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  unsigned long long t, w, b;
  cin >> t >> w >> b;
  unsigned long long pq = gcd(w, b);
  if (t < min(w, b))
    cout << 1 << '/' << 1 << endl;
  else if (t / (w / pq) < b) {
    unsigned long long ans = 0, itung;
    itung = (min(w, b) - 1);
    ans += itung;
    unsigned long long ha = gcd(ans, t);
    if (ans != 0)
      cout << ans / ha << '/' << t / ha << endl;
    else
      cout << 0 << '/' << min(t, min(w, t)) << endl;
  } else {
    unsigned long long kpk = w * (b / pq);
    unsigned long long ans = 0, itung;
    itung = (min(w, b) - 1);
    ans += itung;
    if (t % kpk < itung) {
      ans += (((t / kpk) - 1) * (itung + 1));
      ans += (t % kpk + 1);
    } else
      ans += ((t / kpk) * (itung + 1));
    unsigned long long ha = gcd(ans, t);
    if (ans != 0)
      cout << ans / ha << '/' << t / ha << endl;
    else
      cout << 0 << '/' << min(t, min(w, t)) << endl;
  }
}
