Please choose the correct ending to complete the given sentence: Travel: [header] How to enroll in a frequent flier program [title] Select an airline that offers numerous flights out of your nearest airport. [step] It's best to use a single airline for most of your flights so you want accrue mileage faster. It also will be easier to redeem miles if there are many flights to choose from.

Ending1: [title] Look at how many miles you must fly before you can redeem them for a free flight. [step] Choose an airline that doesn't require flying more miles than other airlines. Ending2: Visit the website of your nearest airline for an easy fee. [title] Contact a representative at the airline to arrange the required miles. Ending3: [substeps] If your airline offers several different flights out of the airport, ask your attendant for a ticket. Consider connecting with alternate airlines so that you can switch your flights based on opportunity. Ending4: Try to pick one that allows you to stay overnight. [substeps] Flights on multiple airlines can sometimes be crowded so if possible make sure to pick an airline that is just as busy as every other airport in your field.

Answer format: ending1/ending2/ending3/ending4