#include <bits/stdc++.h>
using namespace std;
const long long inf = 9e18 + 7;
long long gcd(long long a, long long b) {
  if (!b) return a;
  return gcd(b, a % b);
}
int main() {
  long long t, c, w, b;
  cin >> t >> w >> b;
  if (w < b) swap(w, b);
  if (b / gcd(b, w) > t / w)
    c = inf;
  else {
    c = w / gcd(w, b);
    c *= b;
  }
  long long ted = t / c;
  ted *= (b - 1);
  ted += t / c;
  long long d = t % c;
  ted += min(b - 1, d);
  long long g = gcd(ted, t);
  cout << ted / g << "/" << t / g << endl;
}
