Main.java

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int[][] array = new int[in.nextInt()][in.nextInt()];
        for (int i = 0; i < array.length; i++) {
            for (int j = 0; j < array[i].length; j++) {
                if (i % 2 == 0) {
                    array[i][j] = i * array[i].length + j;
                } else {
                    array[i][j] = (i + 1) * array[i].length - j - 1;
                }
            }
        }

        outArray(array);
    }

    static void outArray(int[][] array) {
        for (int[] i : array) {
            for (int value : i) {
                System.out.printf("%3d", value);
            }
            System.out.println();
        }
    }
}