SPEAKER 1: OK, so our fifth puzzle of this year was called Liar Liar. And among the responses we received, about 1,200 or 1,300 were correct, and 300 were good guesses, but not quite correct. So let's hear from our friends at Meta on how to solve this puzzle. 

CAMERON BATES: Go ahead and share Liar Liar. Again, I was one of the co-authors of this puzzle, along with Alisa. 

This puzzle is a very standard liars and truth teller style puzzle. But more often than not, you're only given two people that you have to solve. 

Well, we wanted to make it a little harder. So we gave you 15 instead. But the idea is still the same-- some of these folks are always going to tell the truth, and some of them are always going to lie, and you've got to figure out who is who. 

There's multiple ways to solve this puzzle. We're going to go ahead and we're going to walk through one of them. But just know that there are other different methods that you could use to logic out who's a truth teller and who's a liar. 

So we can first start with Rachel. Rachel announced that Isabelle, Laura, and herself are all liars. If Rachel was a truth teller, this statement would be false because a truth teller can't say that they are a liar. So we know by definition that Rachel must be a liar. And therefore, at least either one of Isabelle or Laura must be telling the truth. But we don't know anything more about that yet. We'll come back to that later. 

There's one other statement that gives us some information right away. Carla says that Marcus would say that I'm a truth teller. There's two options. Either Carla is a liar, in which case she's lying about what Marcus would say. So if Carla is a liar, then Marcus would say that she is a liar if he's telling the truth. And since she says he's telling the truth, he must be telling the truth because she would lie about him saying that she is a truth teller. 

This is very difficult to explain in words. If you want to grab a pen and paper and spend a little bit of time afterwards with this one, I hope that you can trust me that this is true. 

The alternative option is that Carla's a truth teller, and then this is much more straightforward. Carla is a truth teller, Marcus says she's a truth teller, Marcus is a truth teller. So we don't know whether Carla's telling the truth. We do know that Marcus is a truth teller. 

Using that, we can start making a little bit more progress. Eric claims that all the women are liars. And we don't know whether Laura or Isabella is telling the truth, but we know at least one of them is. So we know that Eric must be a liar. 

Next, Isabelle says that Marcus is married to her, and she denies it. But we know that Marcus is a truth teller, so we know that Isabelle must be a liar. 

And finally, going back to Rachel's statement, if Isabelle is a liar, Laura must be a truth teller because we know at least one of the two of them is a truth teller. 

So great. We've got 5 out of 15 done. Let's keep going. 

Now we know that Laura is a truth teller. She says exactly one of myself, Eric, and Bob are liars. We know this is true. We know that Eric is a liar. Therefore, Bob must be a truth teller. 

Bob says relatively straightforwardly, I agree with Jason. We appreciate Bob for giving us a relatively easy clue. This means that Jason must also be a truth teller. 

And then John says that all liars names start with vowels. But we know that Rachel is a liar, so therefore, John must also be a liar. 

Let's keep going. Jason says there are an even number of truth tellers. This gets us into even/odd cardinality. Therefore, when you have an odd minus an even, you get an odd number. So we know that there must be either an even number of truth tellers and an odd number of liars, or an odd number of truth tellers and an even number of liars. 

In our case, we know that Rebecca's statement that there are an odd number of liars must be true given that Jason is telling us the truth about there being an even number of truth tellers. 

Sam then says, Bob, Jason, and Rebecca are either all truth tellers or all liars. We now know that they're all telling the truth, so Sam is also a truth teller. 

Elliot tells us that there are two more liars than truth tellers, but this can't be true by definition. Because there's a total of 15 people, the difference between the number of truth tellers and the number of liars must be odd. So we know that Elliot is a liar. 

And we're almost done. OK. Sam is a truth teller, and that invalidates Edward's statement that you can't trust people with short names. So therefore, we know that Edward is a liar. 

Now we know that all the people whose names begin with the letter E are liars, so we know that Paul was telling the truth. 

Currently, we have six liars, and that means that Oliver's statement that there are exactly 5 liars is false. So he must also be a liar. 

And finally, there's Carla. We've got Oliver is a liar. So we have 7 liars, 7 truth tellers. And we know that there's an even number of truth tellers and an odd number of liars. So therefore, Carla must be a truth teller. 

Great. We've assigned everyone. And now all these folks are giving us clues about what the final answer is. So, we know that we're looking for a six-letter word. It's an animal. It's a car model. It was featured in 2018 YouTube Rewind, which was not pleasant to watch. It is numerous enough to exceed the number of humans on the planet, has planar symmetry, and there's a superhero named after it. 

Thankfully, it's not larger than a cat. It's not seven letters long. It's not a Pokemon. The letters are not in alphabetical order. It was not one of the previous winning words at the National Spelling Bee. It is not a cereal brand, and does not consist of only one-point tiles in Scrabble. 

There were a few answers that were close to this. We saw jaguar, we saw a beetle, which meet a lot of these clues at the top, but not quite all of them. There's only one thing that met all the clues at the top, and that was the answer to this puzzle-- spider.