PROGRAMMING:Find the longest word
Input an English sentence, the whole English sentence has 4 words, only the last period. Output the longest word. If there are multiple words of the same length, output the first one.
###Input format:
There are four words in an English sentence. There is only one punctuation mark in the whole English sentence.
###Output format:
The longest word in a sentence
###Input example:
```in
i am a boy!
```
###Output example:
```out
boy
```
answer：If there is no answer, please comment
###Input format:
There are four words in an English sentence. There is only one punctuation mark in the whole English sentence.
###Output format:
The longest word in a sentence
###Input example:
```in
i am a boy!
```
###Output example:
```out
boy
```
answer：If there is no answer, please comment