The main idea is:
w1,w2,l1,l2.

r:=6875/2;
dist:=r*arccos(sin(w1)*sin(w2)+cos(w1)*cos(w2)*cos(l2-l1));

I had a problem with parsing the input. It turns out that my logic is fine but got WA3 because it is the first test where the longtitude has 3 digits degrees value.

I don`t remember Pascal. In C expression 6875/2 means 3437, not 3437.5