def check(s):
    for c in s:
        if ord(c) < ord('0') or ord('9') < ord(c):
            return False
    if len(s) > 1 and s[0] == '0':
        return False
    if int(s) > 12345:
        return False
    return True

if check(raw_input()) and check(raw_input()):
    print 'OK'
else:
    print 'NG'