A fair coin is tossed four times, and the random variable X is the number of heads in the first three tosses and the random variable Y is the number of heads in the last three tosses.

Find the joint probability mass function and marginal probability mass function of X and Y.

ON this problem, I did HHHH, HHHT, HHTH,....and so on. Is that how you start off and make a table from there. like there is a 1/13 chance of getting first three heads? I am not completely sure.