Definition: Given a question, generate a paraphrase of that question wihout changing the meaning of it. Your answer should reword the given sentence, but not add information to it or remove information from it. The answer to your question should be the same as the answer to the original question.

Positive Example 1 -
Input: Question: what places in Africa do people speak french?
Output: where in africa do people speak french?

Positive Example 2 -
Input: Question: Hitler became chancellor of Germany in what year?
Output: In which year did Hitler become the chancellor of Germany?

Negative Example 1 -
Input: Question: How long is the Nile river?
Output: Is Nile the longest river?

Negative Example 2 -
Input: Question: Who is the first football player to win seven balon d'ors?
Output: Who won the first balon dor?

Now complete the following example -
Input: Question: which is the world's tallest building ever existed?
Output: 


Output: what is the world's tallest building?