Before revision:  We note that ratio \alpha  -\epsilon can be achieved using  {(1/\epsilon)}^{O(1/\epsilon^4)}n\log n value oracle calls, but this algorithm is impractical already for large } values of \epsilon.
After revision:  We note that ratio \alpha -\epsilon can be achieved using {(1/\epsilon)}^{O(1/\epsilon^4)}n\log ^2 n time, and hence, is of theoretical interest only as } values of \epsilon.