int binary_search1(int l,int r)
{
    while(l<r)
    {
        int mid = l + r >> 1;
        if (check(mid)) r = mid;
        else l = mid + 1;
    }
    return l;
}
int binary_search2(int l,int r)
{
    while(l < r)
    {
        int mid = l + r + 1 >> 1;
        if(check(mid))l=mid;
        else r=mid - 1;
    }
    return l;
}