How do i use the pigeon hole principle for these questions?
A drawer contains 6 pairs of black, 5 pairs of white, 5 pairs of red, and 4 pairs of green socks.
(a) How many single socks do we have to take out to make sure that we take out two socks with the same color. (pigeonhole)
(b) How many single socks do we have to take out to make sure that we take out two socks with diļ¬erent colors? (not really pigeonhole)