A = input()
B = input()

nums = '0123456789'

def check(s):
    for ss in s:
        if ss in nums:
            continue
        else:
            return False
    # leading-zero 判定
    if len(str(int(s))) != len(s):
        return False
    # 大きさ判定
    return 0 <= int(s) <= 12345

if check(A) and check(B):
    print('OK')
else:
    print('NG')