Crossing the river

There is one ferryman, one cow, one tiger and one haystack. The ferryman wants to bring all of them across the river side but he doesn't know which to bring across the river side first. The ferryman has a tiger-proof clothes so the tiger can not eat the him and we all know that the cow would eat the haystack, the tiger wouldn't eat the haystack, the tiger would definitely eat the cow if the ferryman isn't there. Let 's just say that the ferryman is smart and willing to get rid of them. He is willing to get them across the river side and bring them back over and over again so as to get all of them across the river side. The moment the tiger gets across the river ,he will run away freely to the wood. How will he get them across the river? He will bring the ... to the river side and come back to get the... to bring across the river, then he will bring the ... back to get the ... across the river side, finally he will bring the ... to the other side of the river. If the previous answer is the same to next answer, it will only show the answer one time.