Preparing data from sawtooth

Hey,
I read your post in the Rstan forum (https://discourse.mc-stan.org/t/speeding-up-a-hierarchical-multinomial-logit-model/1538) and I was wondering if there was a chance that you can show to actually prepare the data from the cho file in stan format. I know how to read in the data, however, not sure how to get the YB and YW.
I would be happy for any help.

Thanks a lot in advance
Joshua