题解 | #走方格的方案数#

def xx(a, b, c, d):
    if a == c or b == d:
        return 1
    else:
        return xx(a + 1, b, c, d) + xx(a, b + 1, c, d)


while True:
    try:
        m, n = map(int, input().split())
        print(xx(0, 0, m, n))
    except:
        break