Picking out certain elements in an matrix

Suppose I have  a matrix of data

A

1  2 3
4  5 6
7  8 9


And I have a vector of indexes 2,1,3

For  row 1 of matrix A I want the 2nd element  2
For  row 2 of matrix A I want the 1st element  4
For  row 3 of matrix A I want the 3rd element 9.