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