#include <bits/stdc++.h>
using namespace std;
unsigned long long inf = 18e18 + 1;
unsigned long long t, w, b;
unsigned long long lcm(unsigned long long a, unsigned long long b) {
  unsigned long long c = 0;
  unsigned long long R = a;
  unsigned long long O = b;
  while (b) {
    c = a % b;
    a = b;
    b = c;
  }
  if (inf / O < R / a) return inf;
  return R / a * O;
}
unsigned long long gcd(unsigned long long a, unsigned long long b) {
  unsigned long long c;
  while (b) {
    c = a % b;
    a = b;
    b = c;
  }
  return a;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> t >> w >> b;
  unsigned long long numi = t;
  unsigned long long numar =
      min(w, b) * (t / lcm(w, b)) + min(min(w, b), t % lcm(w, b) + 1) - 1;
  cout << numar / gcd(numar, numi) << "/" << numi / gcd(numar, numi) << '\n';
  return 0;
}
