题解 | #走方格的方案数#

list1=input().split()

def func(x,y):
    if x < 0 or y < 0:
        return 0
    elif x == 0 or y == 0:
        return 1
    else:
        return func(x-1, y)+func(x, y-1)

print(func(int(list1[0]),int(list1[1])))