>>By my understanding of the question the 4th line will result in the missionary being eaten
>
>>>(c=cannibal, m=missionary)
>>>left - on boat - right
>>>cccmmm -
>>>ccmm - cm
>>>ccmm - m - c
>>>cmm - cm - c
>>----------^^^^^^
>
>>2 Canibals and 1 missionary - Stew!
>
>The cm is a cannibal and a missionary on the boat, and one cannibal on each back of the river.
>

And once the boat lands on the opposite side of the river, there are two cannibals and one missionary. I had thought too originally that those in the boat didn't count, but if you look in the other branch of this thread, they do. You have to include them with the people on the shore they land on.