There were 100 prisoners which were asked to stand in a line such that the 100th one can see all, 99th one can see the other 98 and so on. There are two sets of cap Black and White. The king decides to put these caps on each of the prisoners(the prisoner can't see his cap but can see all people standing before him caps) randomly and then the king asked each of them to tell their cap color starting from the 100th prisoner, then 99th and so on. If the prisoner answers correctly, the king leaves him otherwise the prisoner is shot dead. If the prisoners are allowed to formulate a strategy, how many prisoners can be saved.

NOTE: Every prisoner can hear every priosoner's answer