everest% cc main2.c list1.c list2.c
main2.c:
list1.c:
list2.c:
everest% 

everest% a.out
Create list with a, c, d, l & p
<"a","c","d","l","p">

Remove "d"
<"a","c","l","p">

Create second list with a, b, d, f, g, l, m, n, x & y
<"a","b","d","f","g","l","m","n","x","y">

Merge the two lists
<"a","b","c","d","f","g","l","m","n","p","x","y">
Merged list has 12 items.

Test for membership
   found g
   did not find w
everest%