A = input()
B = input()

num = [str(i) for i in range(10)]
ls = [A, B]

flag = 0
for i in ls:
    if int(i) > 12345:
        flag += 1

for i in ls:
    for j in i:
        if j not in num:
            flag += 1
if flag >= 1:
    None
else:
    for i in ls:
        if len(i) == 1:
            None
        else:
            if i[0] == '0':
                flag += 1
if flag == 0:
    print('OK')
else:
    print('NG')