We define the usage of capitals in a word to be right when one of the following cases holds:

- All letters in this word are capitals, like `"USA"`.
- All letters in this word are not capitals, like `"leetcode"`.
- Only the first letter in this word is capital, like `"Google"`.

Given a string `word`, return `true` if the usage of capitals in it is right.

Example 1:

    Input: word = "USA"
    Output: true

Example 2:

    Input: word = "FlaG"
    Output: false

Constraints:

- `1 <= word.length <= 100`
- `word` consists of lowercase and uppercase English letters.