X, Y = [abs(int(x)) for x in input().split(' ')]

def cal(x, y):
    x = abs(x)
    y = abs(y)
    if y > x:
        x, y = y, x
    
    x -= 2
    y -= 1
    
    return x, y
    
if X == 0 and Y == 0:
    print('YES')

for _ in range(3):
    X, Y = cal(X,Y)
    if X == 0 and Y == 0:
        print('YES')
        break
else:
    print('NO')