help regarding for loop

Hello everyone, anyone knows how i can make this work using for loop or any other method, the matris at the end is supposed to be

z=[1 1 1 2 1 5 7;0 2 2 1 1 3 6;0 0 2 2 2 3 -8;0 0 0 1 1 6 8]

below is the code

Axb=[1 1 1 2 1 5 7;1 2 2 1 1 3 6;1 3 3 0 1 6 6;1 2 2 2 2 3 -8;1 1 1 1 1 6 8;3 5 9 3 4 3 1;2 2 5 1 8 9 5];

z=zeros(length(Axb),length(Axb));

z(1,:)=Axb(1,:);

Axb=Axb(2:end,2:end);

z=zeros(length(Axb),length(Axb));

z(2,:)=Axb(1,:);

z=zeros(length(Axb),length(Axb));

z(3,:)=Axb(1,:);

Answer 1

[Voss]

Axb=[1 1 1 2 1 5 7;1 2 2 1 1 3 6;1 3 3 0 1 6 6;1 2 2 2 2 3 -8;1 1 1 1 1 6 8;3 5 9 3 4 3 1;2 2 5 1 8 9 5];

z = Axb(1,:);
z(2,2:end) = Axb(2,2:end);
z(3,3:end) = Axb(4,3:end);
z(4,4:end) = Axb(5,4:end);