31:59 Basically, the reason why you can solve this problem, you can make a finite automaton which recognizes the language B, is because that finite automaton is going to keep track of the parity of the number of 1'sit's seen before. This has two states, one of them remembering that it's seen an odd number of 1's so far,the other one remembering it's seen an even number of 1's before. And that's going to be typical for these automata,finite automata. There's going to be several different possibilities that you may have to keep track of as you're reading the input, and there's going to be a state associated with each one of those possibilities. So if you're designing an automaton, you have to think about-- as you're processing the input-- what things you have to keep track of. And you're going to make a state for each one of those possibilities41:52 Show finite automata equivalent to Regular Expression.####[]