write a go solution for Description:
You are given a tree with n vertices. You are allowed to modify the structure of the tree through the following multi-step operation:

1. Choose three vertices a, b, and c such that b is adjacent to both a and c.
2. For every vertex d other than b that is adjacent to a, remove the edge connecting d and a and add the edge connecting d and c.
3. Delete the edge connecting a and b and add the edge connecting a and c.

As an example, consider the following tree:

The following diagram illustrates the sequence of steps that happen when we apply an operation to vertices 2, 4, and 5:

It can be proven that after each operation, the resulting graph is still a tree.

Find the minimum number of operations that must be performed to transform the tree into a star. A star is a tree with one vertex of degree n-1, called its center, and n-1 vertices of degree 1.

Input Format:
The first line contains an integer n (3<=n<=2*10^5)  — the number of vertices in the tree.

The i-th of the following n-1 lines contains two integers u_i and v_i (1<=u_i,v_i<=n, u_ineqv_i) denoting that there exists an edge connecting vertices u_i and v_i. It is guaranteed that the given edges form a tree.

Output Format:
Print a single integer  — the minimum number of operations needed to transform the tree into a star.

It can be proven that under the given constraints, it is always possible to transform the tree into a star using at most 10^18 operations.

Note:
The first test case corresponds to the tree shown in the statement. As we have seen before, we can transform the tree into a star with center at vertex 5 by applying a single operation to vertices 2, 4, and 5.

In the second test case, the given tree is already a star with the center at vertex 4, so no operations have to be performed.. Output only the code with no comments, explanation, or additional text.