#include <bits/stdc++.h>
using namespace std;
long long t, w, b;
long long s, k;
long long gcd(long long x, long long y) {
  if (x < y) swap(x, y);
  if (y == 0) return 1;
  return (x % y ? gcd(y, x % y) : y);
}
int main() {
  cin >> t >> w >> b;
  long long d = gcd(w, b);
  if (b / d <= t / w) {
    d = w * (b / d);
    s = min(w, b) * (t / d);
    if (t % d < min(w, b) - 1) s -= (min(w, b) - t % d - 1);
  }
  s = s + min(min(w, b), t + 1) - 1;
  if (s == 0) {
    cout << "0/1" << endl;
  } else {
    k = gcd(s, t);
    cout << s / k << "/" << t / k << endl;
  }
  return 0;
}
