#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b);
int main() {
  long long t, w, b;
  cin >> t >> w >> b;
  long long tie = 0;
  long long total = t;
  bool overflow = false;
  long long gcdValue = gcd(w, b);
  if (LLONG_MAX / double(w) < double(b) / gcdValue) overflow = true;
  long long lcm = b / gcdValue * w;
  tie += min(w, b) * (t / lcm);
  if (t % lcm < min(w, b))
    tie += t % lcm;
  else
    tie += min(w, b) - 1;
  if (overflow == true) {
    if (t < min(w, b)) {
      tie = 1;
      total = 1;
    } else
      tie = min(w, b) - 1;
  }
  long long gcdans = gcd(tie, total);
  tie /= gcdans;
  total /= gcdans;
  cout << tie << '/' << total << endl;
  ;
  return 0;
}
long long gcd(long long a, long long b) {
  if (a % b == 0) return b;
  if (b % a == 0) return a;
  return gcd(max(a, b) % min(a, b), min(a, b));
}
