vector difference

Dear all,

I was trying to find the difference of two vectors(which is rather easy I
guess in C++), say

real :: a(4) = (/1.,2.,3.,4./)
real :: b(1) = (/2., 3./)

result is to be

res = (/1., 4./)

I wondered if there is a quick way to accomplish this through intrinsic
functions?

I am sorry that I do not have a code to post yet. I did some tries
however none is concluded yet.

My best,
.