#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int m, long long int n) {
  if (m % n == 0) return n;
  return gcd(n, m % n);
}
int main() {
  long long int t, b, w, ans;
  ans = 1;
  cin >> t >> b >> w;
  long long int g = gcd(b, w);
  if (t / b >= w / g) {
    long long int small = b * (w / g);
    ans = (t / small + 1) * min(b, w) - 1;
    if (min(b, w) > t % small) {
      ans = ans - (min(b, w) - 1 - t % small);
    }
  } else {
    ans = min(min(b, w) - 1, t);
  }
  if (ans != 0) {
    g = gcd(t, ans);
    cout << ans / g << "/" << t / g << "\n";
  } else {
    cout << 0 << "/" << 1 << "\n";
  }
  return 0;
}
