Four Things in Desert Island

If stranded on a desert island, I would want a table knife. May be I can use knife to protect me too meet some danger animal or I can use knife to cut cactus for water. Beside knife, I want to carry a cell phone, lap top, credit card and umbrella. Why do I choose these four things? First of all, I can use cell phone talk to my family or my friends. Also, I can use cell phone and lap top to use internet. Moreover, I can use credit card to go shopping on internet. Finally, I afraid sun burn, so an umbrella would be a good tool to protect sun shine.