#include <bits/stdc++.h>
using namespace std;
const int N6 = 1e6 + 6, N3 = 1e3 + 6, oo = 1e9 + 9;
long long t, n, m, ans;
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  ios_base ::sync_with_stdio(0);
  cin >> t >> n >> m;
  if (n < m) swap(n, m);
  long long ggg = gcd(n, m);
  if (m / ggg > t / n) {
    ans = min(m - 1, t);
  } else {
    long long lcm = m / ggg * n;
    ans = (((t / lcm) + 1) * m) - 1;
    if (t % lcm < m) ans -= m - (t % m) - 1;
    if (ans > t) ans = t;
  }
  long long g = gcd(t, ans);
  cout << ans / g << "/" << t / g;
  return 0;
}
