int N, M, D;
    cout << "当前星期几? "; // 星期日是0
    cin >> N;
    cout << "求多少天后? "; // 输入正整数
    cin >> M;

    D = ____________;
    if (____________)
        printf("%d天后是星期日", M);
    else
        printf("%d天后是星期%d", M, D);