If I have a vector and I initialize it like this. How do I access just the first part of the point separately and second separately. 

```
vector<Point2i> cent_i(1); // how do i initialize with a point like (1,2 )
cent_i[0][0] = (floor( s.width/2)); //TRYING TO change the points
cent_i[0][1] = (floor( s.height/2));

```

I don't know if I am doing this right