>>235 python
import string
A26 = set(string.ascii_uppercase)
print(A26.difference(set('BCDEFGHIJKLMNOPQRSTUVWXYZ')).pop()) #-> A
print(A26.difference(set('YIZFOADLMWCRUTGSVQKJEHNBP')).pop()) #-> X
import string
A26 = set(string.ascii_uppercase)
print(A26.difference(set('BCDEFGHIJKLMNOPQRSTUVWXYZ')).pop()) #-> A
print(A26.difference(set('YIZFOADLMWCRUTGSVQKJEHNBP')).pop()) #-> X