data ls4a;
  input y a b c;
cards;
3 1 1 1
5 2 1 2
11 3 1 3
17 4 1 4
7 2 2 1
14 3 2 2
17 4 2 3
5 1 2 4
12 3 3 1
21 4 3 2
5 1 3 3
9 2 3 4
17 4 4 1
9 1 4 2
7 2 4 3
13 3 4 4
;
run;