How to write code in pascal?

Question

Pascal

type town = (a,b,c,d,e,f,g,h);
towns = set of towns;
path = array [town] of towns;
Describe the procedure travel(P,H,K), which, given flights P (P[x] is the set of cities that can be reached by bus from city x in one flight), determines K, the set of cities that can be reached by bus (in one flight or via other cities) from city H.