#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  long long t, w, b, k;
  cin >> t >> w >> b;
  k = t;
  long long c = gcd(w, b);
  c = w / c * b;
  long long ans = 0;
  if (c < 1e18 && c > 0) {
    long long a = t / c;
    b = min(w, b);
    ans = a * b;
    t = t % c;
  }
  if (t < min(w, b))
    t = t;
  else
    t = min(w, b) - 1;
  ans += t;
  t = gcd(ans, k);
  cout << ans / t << "/" << k / t << endl;
  return 0;
}
