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