#include <bits/stdc++.h>
using namespace std;
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  if (b == 0) {
    return a;
  }
  return gcd(b, a % b);
}
bool fun(unsigned long long t, unsigned long long a, unsigned long long b,
         unsigned long long hcf) {
  b /= hcf;
  unsigned long long fac = t / b;
  if (fac < a) {
    return false;
  }
  return true;
}
unsigned long long search(unsigned long long pivot, unsigned long long low,
                          unsigned long long high, unsigned long long t) {
  unsigned long long mid = (low + high) / 2;
  unsigned long long curr = pivot + mid;
  if (curr <= t) {
    if (mid == high || curr + 1 > t) {
      return mid;
    }
    return search(pivot, mid + 1, high, t);
  }
  return search(pivot, low, mid - 1, t);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  unsigned long long t, w, b;
  cin >> t >> w >> b;
  unsigned long long hcf = gcd(w, b), occ = 1, lcm = -1;
  bool check = fun(t, min(w, b), max(w, b), hcf);
  if (check) {
    lcm = (w / hcf) * b;
    occ += t / lcm;
  }
  unsigned long long counter = (occ - 1) * min(w, b) - 1;
  counter += (search((occ - 1) * lcm, 0, min(w, b) - 1, t) + 1);
  cout << counter / gcd(counter, t) << "/" << t / gcd(counter, t);
}
