2
3 4

3.5

If you start with two ingredients, the only choice is to put both of them in the pot. The value of the ingredient resulting from the ingredients of values $3$ and $4$ is $(3 + 4) / 2 = 3.5$. Printing `3.50001`, `3.49999`, and so on will also be accepted.

3
500 300 200

375

You start with three ingredients this time, and you can choose what to use in the first composition. There are three possible choices: - Use the ingredients of values $500$ and $300$ to produce an ingredient of value $(500 + 300) / 2 = 400$. The next composition will use this ingredient and the ingredient of value $200$, resulting in an ingredient of value $(400 + 200) / 2 = 300$. - Use the ingredients of values $500$ and $200$ to produce an ingredient of value $(500 + 200) / 2 = 350$. The next composition will use this ingredient and the ingredient of value $300$, resulting in an ingredient of value $(350 + 300) / 2 = 325$. - Use the ingredients of values $300$ and $200$ to produce an ingredient of value $(300 + 200) / 2 = 250$. The next composition will use this ingredient and the ingredient of value $500$, resulting in an ingredient of value $(250 + 500) / 2 = 375$. Thus, the maximum possible value of the last ingredient remaining is $375$. Printing `375.0` and so on will also be accepted.