A king wants to get rid of some of his ministers. So he calls them up and tells them his plan for the following day. "You will all be made to stand in a stright line, all facing the same way, along the direction of the line" he says. "I will randomly put hats on your heads which will be one of 2 colors : black or white. Then, starting at one end of the line (from the minister who can see all the others in front of him) I will ask each of you the color of his hat. Those that answer correctly will be spared." The ministers all convene after this announcement to formulate a strategy that will minimize the number of deaths. What would be the best strategy and what is maximum number of deaths it allows ? NOTE the following : 1. The first minister to be questioned can see all the hats except his own. The next can see all but 2, and so on... 2. When questioned, the minister is only allowed a one word answer which must be "black" or "white" and no special intonation is allowed. 3. Every minister can hear the answers provided by those preceding him.