# Enter your code here. Read input from STDIN. Print output to STDOUT
key     = raw_input()
chipher = raw_input()
chipher = chipher.decode('hex')


	
def enc1(string, key):
	xored = ''
	for i in range (0, len(string)):
		xor = ord(string[i])
		for j in range (0, len(key)):
			xor ^= ord(key[j])
		xored += chr(xor)		
	
	return xored.encode('hex')
	
def enc2(string, key):
	xored = ''
	for i in range (0, len(string)):
		xor = ord(string[i]) ^ ord(key[i%len(key)])
		xored += chr(xor)
	
	return xored
	
xored = enc2(chipher, key)
print xored