```
class Solution(object):
def titleToNumber(self, s):
dic = {'A':1,'B':2,'C':3,'D':4,'E':5,'F':6,'G':7,'H':8,'I':9,'J':10,'K':11,'L':12,'M':13,'N':14,'O':15,'P':16,'Q':17,'R':18,'S':19,'T':20,'U':21,'V':22,'W':23,'X':24,'Y':25,'Z':26}
length = len(s)
total = 0
for i in range(length):
total += dic[s[i]]*pow(26,length-i-1)
return total
```