#include <bits/stdc++.h>
long long gcd(long long a, long long b) {
  while (0 < b) {
    a %= b;
    std::swap(a, b);
  }
  return a;
}
int main() {
  long long t, w, b;
  long long m, r;
  std::cin >> t >> w >> b;
  if (w < b) std::swap(w, b);
  m = gcd(w, b);
  if (t / b < w / m)
    m = t + 1;
  else
    m = w / m * b;
  r = t / m * b;
  r += std::min(t % m + 1, b);
  --r;
  m = gcd(t, r);
  t /= m, r /= m;
  std::cout << r << '/' << t << std::endl;
  return 0;
}
