python3

def func():
    while True:
        try:
            string = input().strip()
            result = string[::-1]
            string1 = ""
            for i in range(len(result)):
                if result[i] not in string1:
                    string1 += result[i]
            print(string1)
        except:
            break


if __name__ == "__main__":
    func()