Problem 611. surrounded matrix

With a given matrix A (size m x n) create a matrix B (size m+2 x n+2) so that the matrix A is surrounded by ones:

A = [1 2 3
     3 2 1]

B = [1 1 1 1 1
     1 1 2 3 1
     1 3 2 1 1
     1 1 1 1 1]

or

A = 4

B = [ 1 1 1
      1 4 1
      1 1 1]