设F是由T1,T2,T3三棵树组成的森林，其中T1,T2,T3的结点数分别为n1,n2和n3，与F对应的二叉树为B，则二叉树B的右子树中有_____________个结点（单选） Assume that F is a forest, made up of tree T1, T2, T3, and the node numbers of T1, T2, T3 are n1, n2, n3. Let B be the corresponding binary tree of F, then B's right sub-tree will has __________ nodes. （There is only one correct answer)