# 描述

Transmitting and memorizing information is a task that requires different coding systems for the best use of the available space. A well known system is that one where a number is associated to a character sequence. It is considered that the words are made only of small characters of the English alphabet a,b,c, …, z (26 characters). From all these words we consider only those whose letters are in lexigraphical order (each character is smaller than the next character).

The coding system works like this:

• The words are arranged in the increasing order of their length.
• The words with the same length are arranged in lexicographical order (the order from the dictionary).
• We codify these words by their numbering, starting with a, as follows:
a - 1
b - 2

z - 26
ab - 27

az - 51
bc - 52

vwxyz - 83681

Specify for a given word if it can be codified according to this coding system. For the affirmative case specify its code.

## Input

The only line contains a word. There are some constraints:

• The word is maximum 10 letters length
• The English alphabet has 26 characters.

## Output

The output will contain the code of the given word, or 0 if the word can not be codified.

• intput

• output

# 思路

• 对于长度为$N$的字符串应该先求长度为$N-1$的字符串有多少种。很明显可以看出长度为i的字符串就是从26个字母中选择i个字符组合（因为有大小限制，所以不是排列）。所以长度为$N-1$的字符串有：$sum_{i=1}^{Len-1}C_{26}^{i}$种。
• 对于剩下的，就从a[0]开始，每次计算这个字母开头的单词个数，遍历完就行了。

# 代码

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