PROGRAMMING:Count the number of words (Cixi, 2006)

Input a sentence, the sentence only English words and spaces, each word is separated by one or more spaces, statistics of the number of words in the sentence. English words are composed of uppercase and lowercase letters. If the input word contains other characters, output No. If repeated words are counted only once, and the upper and lower case letters are considered to be the same, for example, 'my' and 'my' and 'my' are the same word.
###Input format:
Enter a sentence on the first line.
###Output format:
Output only one line, output the number of words.
###Input example:
```in
MY name is IS lele
```
###Output example:
```out
four
```







answer：If there is no answer, please comment