def main():
    a = input()
    b = input()
    if check(a) and (check(b) and int(b) <= 12345):
        print("OK")
    else:
        print("NG")
    
def check(s):    
    if s[0] == "0":
        if len(s) > 1:
            return False
    for v in s:
        if ord(v) < 48 or ord(v) > 57:
            return False
    return True

main()