#include <bits/stdc++.h>
using namespace std;
long long htmp;
long long bmm(long long a, long long b) {
  if (b == 0) return a;
  return bmm(b, a % b);
}
long long kmm(long long a, long long b) {
  if (a > b) {
    htmp = a;
    a = b;
    b = htmp;
  }
  return a * (b / (bmm(a, b)));
}
int main() {
  ios_base::sync_with_stdio(false);
  long long t, w, b, kmmm, tmp;
  cin >> t >> b >> w;
  if (w > b) {
    tmp = w;
    w = b;
    b = tmp;
  }
  kmmm = kmm(w, b);
  if (kmmm % w != 0 || kmmm % b != 0 || kmmm == 0) {
    w = (w - 1 > t) ? t : w - 1;
    kmmm = bmm(w, t);
    long long kk1, kk2;
    kk1 = (w) / kmmm;
    kk2 = t / kmmm;
    cout << kk1 << "/" << kk2 << endl;
    return 0;
  }
  long long tef = t - ((t / kmmm) * kmmm) + 1;
  tef = (tef > w) ? w : tef;
  long long res = (t / kmmm) * w - 1 + tef;
  long long res1, res2;
  kmmm = bmm(res, t);
  res1 = res / kmmm;
  res2 = t / kmmm;
  cout << res1 << "/" << res2 << endl;
  return 0;
}
