import java.util.Scanner;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* 多线程，线程交替打印ABCDABCD
*/
public class Test49 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()) {
int n = scanner.nextInt();
CountDownLatch countDownLatch = new CountDownLatch(4);
AlternativePrint alternativePrint = new AlternativePrint();
new Thread(new Runnable() {
@Override
public void run() {
try {
for (int i = 0; i < n; i++) {
alternativePrint.printA();
}
} finally {
countDownLatch.countDown();
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
try {
for (int i = 0; i < n; i++) {
alternativePrint.printB();
}
} finally {
countDownLatch.countDown();
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
try {
for (int i = 0; i < n; i++) {
alternativePrint.printC();
}
} finally {
countDownLatch.countDown();
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
try {
for (int i = 0; i < n; i++) {
alternativePrint.printD();
}
} finally {
countDownLatch.countDown();
}
}
}).start();
try {
countDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println();
}
}
}
class AlternativePrint {
private Lock lock = new ReentrantLock();
private Condition conditionA = lock.newCondition();
private Condition conditionB = lock.newCondition();
private Condition conditionC = lock.newCondition();
private Condition conditionD = lock.newCondition();
private int number = 1;
void printA() {
lock.lock();
try {
if (number != 1) {
conditionA.await();
}
System.out.print("A");
number = 2;
conditionB.signal();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
lock.unlock();
}
}
void printB() {
lock.lock();
try {
if (number != 2) {
conditionB.await();
}
System.out.print("B");
number = 3;
conditionC.signal();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
lock.unlock();
}
}
void printC() {
lock.lock();
try {
if (number != 3) {
conditionC.await();
}
System.out.print("C");
number = 4;
conditionD.signal();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
lock.unlock();
}
}
void printD() {
lock.lock();
try {
if (number != 4) {
conditionD.await();
}
System.out.print("D");
number = 1;
conditionA.signal();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
lock.unlock();
}
}
}
