题解 | #进制转换#

num_hexa=list(str(input()))
if num_hexa[0]=='0' and num_hexa[1]=='x':
    del num_hexa[:2]
#print(num_hexa)
num_hexa.reverse()   # 列表反转
hexa=['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F']
#print(len(hexa))
num=0
#print(num_hexa)
for i in range(len(num_hexa)):
    num=num+hexa.index(num_hexa[i].upper())*(16**i)  # upper() 字母小写转换为大写，数字不变
    i += 1
print(num)