how to make multiple graphs with varying x-axis - Matlab

[poster]

I need to plot multiple graphs in the same y-axis but the x-axis is a bit tricky:
Assuming it goes from 0 to a, increasing by one, it needs to have an overall of (a-1) different intervals; each one of them should finish at a, but it also have to have a different initialisation. Only the first starts by 0, while each next starts by the previous plus one, as in the shape below. Of course, the 2 dashed lines I used to make as clear as I could, are not necessary.

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