how to write this problem

hello everyone and thanks for previous answers. I have the code below

j=[1 2 3]; p=[1 2 1;2 3 1;3 1 2;1 1 2]; now I need to code this:

c(1,3)=p(1,3);

c(2,3)=p(1,3)+p(2,3);

c(3,3)=p(1,3)+p(2,3)+p(3,3);

c(4,3)=p(1,3)+p(2,3)+p(3,3)+p(4,3);

any help would be great

thanks in advance