given two strings s and t which consist of only lowercase letters string t is generated by random shuffling string s and then add one more letter at a random position find the letter that was added in t for example input s abcd t abecd output e explanation e is the letter that was added we use the characteristic equation of xor a xor b xor c a xor c xor b if a c then a xor c 0 and then b xor 0 b ordch return an integer representing the unicode code point of that character chri return the string representing a character whose unicode code point is the integer i we use the characteristic equation of xor a xor b xor c a xor c xor b if a c then a xor c 0 and then b xor 0 b ord ch return an integer representing the unicode code point of that character chr i return the string representing a character whose unicode code point is the integer i
def find_difference(s, t):
    ret = 0
    for ch in s + t:
        
        ret = ret ^ ord(ch)
    
    return chr(ret)