Discrete - time system

Hello, How can add N = 100, N = 50 for length N as stated in the image below? this is my attempt but not sure how add this or modify it?

Any help will be greatly appreciated. Thanks

sys = tf(ones(1,1,1,5));

W0 = 0:0.5:1;    % natural frequencies
zeta = 0.5;        % damping constant
for i = 1:length(W0)
   sys(:,:,1,i) = tf(w0(i)^2,[1 2*zeta*w0(i) w0(i)^2]);
end

[u,t] = gensig("square",5,20);
lsim(sys,u,t)