import sys

if len(sys.argv) != 3:
    print("Usage: python3 vernam.py [key] [string]")
    sys.exit(1)

key = sys.argv[1]
string = sys.argv[2]

if len(string) != len(key):
    print("Key and string must have the same length")
    sys.exit(1)

encrypted = ""

for i in range(len(string)):
    encrypted += chr(ord(string[i]) ^ ord(key[i]))
    # print(ord(string[i]) ^ ord(key[i]))

print(encrypted)

# python3 vernam.py ABCDEF TOMATE | xargs python3 vernam.py ABCDEF