a = input().strip()
b = input().strip()

def valid(s):
    # Check if all characters are digits
    if not s.isdigit():
        return False
    # Check leading zero
    if len(s) > 1 and s[0] == '0':
        return False
    # Check value range
    num = int(s)
    return 0 <= num <= 12345

ok_a = valid(a)
ok_b = valid(b)

print("OK" if ok_a and ok_b else "NG")