import java.util.*;


public class Main {


	public static void main(String[] args) {

		Scanner s = new Scanner(System.in);
		System.out.println("start math test ? y/n");
		String c = s.next();

		if(c == "n") return;
		else StartMath();







	}

	private static void StartMath() {

		Random r = new Random();
		Scanner s = new Scanner(System.in);

		System.out.println("choose a level 1-3");
		int level = s.nextInt();
		if(level < 1 || level > 3) return;
		System.out.println("I will ask you 20 question and you need to answer the most fast as you can - and right!");

		Date date = new Date();
		long d = date.getTime();

		int num1=0,num2=0;
		int correct=0;
		for(int i = 1;i <= 20;i++) {
			if(level == 1) {
				num1 = r.nextInt(10);
				num2 = r.nextInt(10);
			}
			else if(level == 2) {
				num1 = r.nextInt(100);
				num2 = r.nextInt(100);
			}
			else {
				num1 = r.nextInt(1000);
				num2 = r.nextInt(1000);
			}

			System.out.println("Question " + i);
			System.out.println(num1 + "-" + num2 + "=?");
			int answer = s.nextInt();

			if(answer == num1-num2) {
				correct++;
				System.out.println("You answer right! good job!");
			}
			else System.out.println("Your answer was wrong!");


		}

		System.out.println("You answer " + correct + " correct and " + (20-correct) + " wrong!");
		Date date2 = new Date();
		long d2 = date2.getTime();
		System.out.println("it take you " + (d-d2));
	}


}