Loose Subsequence Maximum Sum

Given a string s consisting only of lowercase letters, we define a loose subsequence as follows. Let t be a subsequence of s with positions p₁, p₂, ..., p_k corresponding to characters in s. The subsequence t is called a loose subsequence if for all i > 1 the following holds:

$$p_i - p_{i-1} \geq 2$$

The value of a subsequence is defined as the sum of the values of the chosen characters, where the letters from a to z have values from 1 to 26 respectively, i.e.,

$$\text{value}(c) = \text{ord}(c) - \text{ord}('a') + 1, \quad c \in \{a,\dots,z\\}$$

Your task is to compute the maximum value attainable by any loose subsequence of s.

inputFormat

The input consists of a single line containing the string s (only lowercase letters).

Format: one string.

outputFormat

Output a single integer, which is the maximum value of any loose subsequence of s.

Format: one integer.

sample

abc

4