Tokens On A Tree

You are given a rooted tree with $N$ nodes numbered $1, 2, \ldots, N$. Node $1$ is the root node. Some of the nodes have a token in them. In one move, you can choose a non-root node that has a token, but its parent doesn't, and move the token from this node to its parent. What is the maximum number of moves you can make? **Note:** When a token is moved out of a node, the node becomes empty, and