chess

print("""This program determines the color of the chess board box that the user names.
In order to get thr result , one must enter the correct name of the square like 'e4' or 'b6'
i.e the first character will be a lower case letter between a-h followed by a digit between 1-8""")
name = input("Please enter the square name: ")
letters = ["a", "b", "c", "d", "e", "f", "g", "h"]
letter = name[0]
num = int(name[1])
if letter not in letters or num > 8 or num < 1:
    print("Invalid Input!!!  Such box doesn't exist.")
    exit()

if (num + letters.index(letter)+1) % 2 == 0:
    print(f'Square {name} is black')
else:
    print(f'Square {name} is white')