a = input()
b = input()
input_list = [a, b]

num_list = list(range(0, 10))
count = 0

for i in range(2):
    cur_str = input_list[i]
    judge_list = [int(c) in num_list for c in cur_str]
    
    if all(judge_list):
        if len(cur_str) == 1:
            count += 1
        else:
            if cur_str[0] != '0' and int(cur_str) <= 12345:
                count += 1
            
if count == 2:
    print('OK')
else:
    print('NG')