Convert string parameters from response to integers

Hi, I’m currently testing Star Wars API and I wonder if it’s possible to convert string parameters (from multiple objects in array) to integers.

In response we get 39 vehicles, each one has “crew”, but this parameter is string (and I’m sure that each value is number without quotation marks).
I would like to convert all crew parameters to integers and then execute some tests with them. How can I do it? Are there some methods which I can use in Tests or Pre-request script tabs?