Please choose the correct ending to complete the given sentence: Health: [header] How to prevent headaches after air travel [title] Try ibuprofen. [step] Oftentimes, headaches that occur during or after flight are due to a sudden change in altitude. The painkiller ibuprofen may effectively prevent altitude related headaches before they begin.

Ending1: [substeps] To make sure ibuprofen is safe for you, purchase ibuprofen in the main aisle of your car. To take it, only apply to the wound, or pull it out before you hit the ground. Ending2: [substeps] Follow the steps above for ibuprofen. If you do not already have a painkiller, purchase one in health food stores. Ending3: Only use an effective ibuprofen for up to one month or more. This should not interfere with your daily flight. Ending4: [substeps] In a recent study, hikers preparing for a high altitude journey were given doses of ibuprofen in the 24 hours prior to their journey. A little over 40% of hikers who took ibuprofen developed altitude-related headaches and nausea.

Answer format: ending1/ending2/ending3/ending4