Give a context-free description for the set of words obtained by intercaling two words $w_1,w_2$ over $\{a,b\}$ with the same length and with no occurrences of $aa$ in $w_2$, and such that for each two prefixes $x_1,x_2$ of $w_1,w_2$, respectively, of the same length, it holds that $x_1$ has more or equal occurrences of $a$ than $x_2$. Intercaling $n$ words $w_1,\ldots,w_n$ over $\{a,b\}$ and with the same length gives as result a word whose sequence of symbols is: the first symbol of $w_1$, the first symbol of $w_2$, …, the first symbol of $w_n$, the second symbol of $w_1$, the second symbol of $w_2$, …, the second symbol of $w_n$, the third symbol of $w_1$, and so on.