Hi all

I've got two sets of numbers:

a: 1 3 4 7 9 11 13 15 16 18 21 22 25 32 33 36 38 39 41 42 43 44 46 48
49 50
b: 2 3 5 8 9 10 13 16 17 18 20 21 29 30 31 32 35 39 40 45 48 49 50 52
54 55

How would I write a formula that would tell me how many numbers match
from each set? Thanks