int pos[8];

void queen(int n) {

    for (int i = 0; i < 8; i++) {

        pos[n] = i ;

        bool attacked = false;

        for (int j = 0; j < n; j++)

            if (pos[n] == pos[j] || pos[n] + n == pos[j] + j || pos[n] - n == pos[j] - j) {

            attacked = true;

            break ;

        }

        if (attacked)

            continue;

        if (n == 7) {

            return;

        } else {

            queen(n + 1);

        }

    }

}