另一种字符串暴力解法(记忆力不好易忘记常用函数的人适用):直接创建字典进行检索。
#要大笑,要做梦,要与众不同。人生是一场伟大的冒险🐶。

while True:
    try:
        a = input()[2:][::-1]
        dic = {"A":10,"B":11,"C":12,"D":13,"E":14,"F":15,"G":16}
        num = 0
        pos = 0
        for i in a:
            pos+=1
            if i in dic.keys():
                num += dic[i]*16**(pos-1)
            else:
                num+= int(i)*16**(pos-1)
        print(num)
    except:
        break