static noeq record IntPair(int a, int b) {
  public boolean equals(Object o) {
    if (!(o instanceof IntPair)) return false;
    IntPair x =  (IntPair) o;
    return eq(a, x.a) && eq(b, x.b);
  }

  public int hashCode() {
    int h = -672893111;
    h = boostHashCombine(h, _hashCode(a));
    h = boostHashCombine(h, _hashCode(b));
    return h;
  }
}