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.

Restricciones

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.

Ejemplos

Entrada:
phrase = "central-processing unit"

Salida esperada:
expected = "CPU"

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

Salida esperada:
std::string expected = "CPU";

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

Salida esperada:
string expected = "CPU";

Entrada:
phrase = "don't repeat yourself"

Salida esperada:
expected = "DRY"

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

Salida esperada:
std::string expected = "DRY";

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

Salida esperada:
string expected = "DRY";

Referencias

Este reto está adaptado para CodeUtility. Sigue el enunciado y las restricciones indicadas arriba.

• Exercism: Acronym