VERY HARD RIDDLE - good luck!?

Three men are captured by cannibals. The chief, who is in a good mood, decides to give them a chance to live. He puts them in a hut with no mirrors, all facing in a row facing the same direction, one behind the other behind the other. He has five hats - three red, two blue - and he puts one on each man's head.... show more Three men are captured by cannibals. The chief, who is in a good mood, decides to give them a chance to live. He puts them in a hut with no mirrors, all facing in a row facing the same direction, one behind the other behind the other. He has five hats - three red, two blue - and he puts one on each man's head. No man is able to see his hat, but the back two men can see the hats of the people in front of them. Rules: the men can't communicate in any way or turn their heads, but to be set free, one of them must correctly guess their OWN hat color. How do they do it? (Hint: there is logic behind this. Assume that there is silence for a long while, and all the men are very smart.)
Update: As I said, assume there is silence. You've got part one...the back man doesn't know his hat color, because if the front two guys had blue hats, he would know. I won't say any more.
Update 2: To clarify...

1) they can't see the hats that aren't being used.
2) only one person has to guess for all of them to be set free.
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