Give context-free grammars that generate the following languages:

1. The language consisting of balanced parentheses and square brackets, including the empty string. Example: ([[](()[()][[]])])[]((())) .
2. The language containing non-empty strings with an equal number of a's and b's.
3. The language containing strings of the form ww^Rcaⁿb²ⁿ, where w is a string of one or more a's and b's; w^R denotes the reversal of w, and the superscript n stands for any positive integer, meaning that the end of the string should contain one or more a's followed by twice as many b's as a's.