a = input()
b = input()
for c in a:
    if c not in '0123456789':
        print('NG')
        exit()
for c in b:
    if c not in '0123456789':
        print('NG')
        exit()
if a != str(int(a)):
    print('NG')
    exit()
if b != str(int(b)):
    print('NG')
    exit()
if int(a) > 12345:
    print('NG')
    exit()
if int(b) > 12345:
    print('NG')
    exit()
print('OK')