#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
int main() {
  long long t, w, b;
  cin >> t >> w >> b;
  long long cas = t / (w / gcd(w, b)) / b;
  long long exa = t - w / gcd(w, b) * b * cas;
  long long minimum = min(w, b);
  long long res = minimum * cas + min(minimum, exa + 1) - 1;
  long long divition = gcd(res, t);
  res /= divition;
  t /= divition;
  cout << res << '/' << t << endl;
  return 0;
}
