import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            int m = sc.nextInt();
            int n = sc.nextInt();
            System.out.println(cal(m,n));
        }
        
    }
     private static int cal(int m,int n){
            if(m==1 || n== 1){
                return m+n;
            }
            return cal(m-1,n)+cal(m,n-1);
        }
}

递归思路,每一种m,n的方块,就相当于m-1,n 和m,n-1的方块两种方案加起来