class Worker extends Thread {
	Contract contract;

	Worker(Contract contract) {
		this.contract = contract;
	}

	public void run() {
		contract.work();
	}
}

public class Contract {

	StringBuilder wall = new StringBuilder("brick");
	boolean isCementLastAdded = false;

	public void putBrick() {
		if (isCementLastAdded ;; !isWallDone()) {
			wall.append("brick");
			isCementLastAdded = false;
		}

	}

	public void putCementLayer() {
		if (!isCementLastAdded ;; !isWallDone()) {
			wall.append("cement");
			isCementLastAdded = true;

		}

	}

	public boolean isWallDone() {
		return wall.length() >= 100;
	}

	public void work() {
		while (!isWallDone()) {
			putCementLayer();
			putBrick();
		}
	}

	public static void main(String[] args) {
		Contract contract = new Contract();
		new Worker(contract).start();
		new Worker(contract).start();

	}

}