Create the SHIRTS data set. SHIRTS contains the sizes of a particular shirt that is sold during a week at a clothing store, with one observation for each shirt that is sold.

data shirts;
   input Size $ @@;
   datalines;
medium    large
large     large
large     medium
medium    small
small     medium
medium    large
small     medium
large     large
large     small
medium    medium
medium    medium
medium    large
small     small
;