Black and White Tree

You are given an undirected tree having $N$ nodes. The color of each node is either Black or White. In one step, you can choose a node $u$, toggle the color of the chosen node $u$, as well as toggle the colors of all the nodes $v$, such that $\{u, v\}$ is an edge in the tree. Can you find out the minimum number of steps required to make the color of all the nodes black? **Note:** Since the inpu