Alpha | Topcoder Archive

Problem Statement

Limak is a little bear who wants to learn the English alphabet. He tries to say the whole alphabet from 'a' to 'z'. Your job is to stop him when he makes a mistake. Can you check how many first letters he said correctly?

You are given a String s that consists of lowercase English letters. Find how many first characters match the beginning of the English alphabet. The English alphabet looks as follows: abcdefghijklmnopqrstuvwxyz.

Definition

Class:: Alpha
Method:: maxPref
Parameters:: String
Returns:: int
Method signature:: int maxPref(String s)
(be sure your method is public)

Constraints

The number of characters in s will be between 1 and 26, inclusive.
Each character in s will be a lowercase English character ('a' - 'z').

Examples

```
"abctyf"
```
```
Returns: 3
```
The first three characters match: a, b, c.
```
"abcdefghijklmnopqrstuvwxyz"
```
```
Returns: 26
```
All 26 characters match the English alphabet exactly.
```
"zyx"
```
```
Returns: 0
```
```
"abcdegfhijk"
```
```
Returns: 5
```
Characters 'f' and 'g' are swapped, so we only accept first five characters (abcde).
```
"ba"
```
```
Returns: 0
```
```
"aabc"
```
```
Returns: 1
```
```
"abcdefghijklmno"
```
```
Returns: 15
```

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