Can I have a map with two keys in STL?

Hello,

If I make an array of strings, a={"apple","banana",etc..}, I can easily find the string corresponding to a given index - ex. a[1].

If I make a map, mapa, I can easily find the index corresponding to a string - ex. a.find("apple").

Is there a container that lets me do both? (And the indexes must remain from 0 to N)

I can probably implement one, but I'm trying to learn STL, so I'm looking for an STL way.

Thanks!