How can i replace elements from first matrix to second without changing the size of second matrix?

I have a matrix

    A=[1 3 4 6];
and
    B=[1 5 6 9 10 12 18];

the length of A is 4 and B is 7. Now i want to change the elements of B by changing first 4 elements of A in B.Final output i want is

    B=[1 3 4 6 10 12 18]
How it can be done?

Please help me...

Answer 1

[the cyclist]

B(1:4) = A;

or more generally

B(1:length(A)) = A;

[suchismita]

thank you so much...