class BaseBSearch
{
    static public int Go(int[] x, int n, int t)
    {
        int l = 0, u = n - 1, p = 0, m = 0;
 
        while (true) {
            if (l > u) {
                p = -1;
                break;
            }
            m = (l + u) /2;
 
            if (x[m] <  t) {
                l = m + 1;
            } else if (x[m] == t) {
                p = m;
                break;
            } else if (x[m] >  t) {
                u = m - 1;
            }
        }
        return p;
    }
}