Acronym Generator

Create an acronym from the first letter of every word, in uppercase. Spaces and hyphens separate words. Remove every other punctuation mark and digit without adding a separator; an apostrophe inside a word does not start another word. Ignore empty pieces.

Implement acronym_generator(phrase).

Input

phrase: The phrase to shorten.

Output

Return the uppercase initials in their original order.

制約

0 ≤ phrase length ≤ 10,000. Input contains ASCII letters, digits, spaces, and punctuation; no tabs or line breaks. A phrase with no letters returns empty text.

例

入力：
phrase = "central-processing unit"

期待される出力：
expected = "CPU"

入力：
std::string phrase = "central-processing unit";

期待される出力：
std::string expected = "CPU";

入力：
string phrase = "central-processing unit";

期待される出力：
string expected = "CPU";

入力：
phrase = "don't repeat yourself"

期待される出力：
expected = "DRY"

入力：
std::string phrase = "don't repeat yourself";

期待される出力：
std::string expected = "DRY";

入力：
string phrase = "don't repeat yourself";

期待される出力：
string expected = "DRY";

参考資料

この課題はCodeUtility用に調整されています。上記の説明と制約に従ってください。

• Exercism: Acronym