An alien force has invaded the realms of the earth. All they plan is the destruction of the entire planet. However, they have given humans a chance. They picks up ten intelligent most humans (you are one of them) and take them in a pitch black room. There is nothing you can see in the total darkness. The aliens place a hat on every human. The hats are of two colors - pink and green. After they place all the hats, the lights are turned on.
You are not allowed to see your own hat. The circulation of the hat is totally random with any kind of possible combination. The aliens start from the back and ask, "What is the color of hat you are wearing?" Everyone is allowed to hear the answer. If he gives the correct answer, he will be allowed to live and save the people but if he gives the wrong answer, he will be killed mercilessly and the people you represent will be killed.
What will you do to save as many lives as you can?