Double y axis plot when two data sets are not starting from the same time

I have two data sets A and B. A = 20x1 and B=11x1. I want to make double y axis plot with these datasets. But the plot should be start with A at first. From the 10th point B will start. Means A and B will not start together.

Answer 1

[KSSV]

A = rand(20,1);
B = rand(11,1);
idx = 1:length(A) ; 
plot(idx,A,'r')
hold on
plot(idx(10:end),B,'b')
legend('A','B')