A2 B2 C2 D2 2.you draw 2 cards go to step 3 or 4

A3 B3 C3 D3 3.if they are the same in either letter or number put them asside go to step 2

A4 B4 C4 D4 4.if they are not the same in either letter or number go to step 1 and restart

Win.if all 16 cards are set asside

the question is what is the probability of winning

please keep the denominator as 16!

i have tried it using branching probability but it had too many branches

i make puzzles in my free time