import java.util.*;
import java.util.zip.*;
import java.util.List;
import java.util.regex.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
import java.util.concurrent.locks.*;
import java.util.function.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import javax.swing.table.*;
import java.io.*;
import java.net.*;
import java.lang.reflect.*;
import java.lang.ref.*;
import java.lang.management.*;
import java.security.*;
import java.security.spec.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.awt.geom.*;
import javax.imageio.*;
import java.math.*;
import java.time.Duration;
import java.lang.invoke.VarHandle;
import java.lang.invoke.MethodHandles;

class main {

static LongPairCollector longPairCollector(IVF2_Long onCompletion) {
  return new LongPairCollector() {
    void complete(long a, long b) {
      { if (onCompletion != null) onCompletion.get(a, b); }
    }
  };
}
interface IVF2_Long {
  void get(long a, long b);
}



// assumes that each set function is called only once
static class LongPairCollector {
  volatile long a;
  volatile long b;
  volatile int counter;
  
  // statically get var handles
  private static final VarHandle vhCounter;
  static { try {
    var l = MethodHandles.lookup();
    vhCounter = l.findVarHandle(LongPairCollector.class, "counter", int.class);
  } catch (Exception __e) { throw rethrow(__e); } }
  
  void setA(long a) { this.a = a; incCounter(); }
  void setB(long b) { this.b = b; incCounter(); }
  
  LongConsumer setterForA() { return a -> setA(a); }
  LongConsumer setterForB() { return b -> setB(b); }
  
  private void incCounter() {
    if (((int) vhCounter.getAndAdd(this, 1))+1 == 2)
      complete(a, b);
  }
  
  // can override or swap
  transient  IVF2<Long, Long> complete;
void complete(long a, long b) { if (complete != null) complete.get(a, b); else complete_base(a, b); }
final void complete_fallback(IVF2<Long, Long> _f, long a, long b) { if (_f != null) _f.get(a, b); else complete_base(a, b); }
void complete_base(long a, long b) {}
}


static interface IVF2<A, B> {
  void get(A a, B b);
}


static RuntimeException rethrow(Throwable t) {
  
  if (t instanceof Error)
    _handleError((Error) t);
  
  throw t instanceof RuntimeException ? (RuntimeException) t : new RuntimeException(t);
}

static RuntimeException rethrow(String msg, Throwable t) {
  throw new RuntimeException(msg, t);
}




static void _handleError(Error e) {
  //call(javax(), '_handleError, e);
}



}