import sys

def main():
    A = input()
    B = input()

    if is_zero_leading(A) or is_zero_leading(B):
        print("NG")
        sys.exit()

    try:
        int_A = int(A)
        int_B = int(B)
        if int_A < 0 or int_A > 12345:
            print("NG")
        elif int_B < 0 or int_B > 12345:
            print("NG")
        else:
            print("OK")
    except ValueError:
        print("NG")

def is_zero_leading(value):
    if value == "0":
        return False
    elif value[0] == "0":
        return True
    else:
        return False

if __name__ == '__main__':
    main()