Definition: In this task, you need to generate an appropriate title for the given summary of some paragraph. The generated title must be short and should include the main topic of the given text. Your summary should be less than 20 words long.
Input: US President Donald Trump has continued to promise to build a wall along the US-Mexico border. But he'll have to get through a lot of obstacles first.

100 days: What might Trump's border wall look like?