N = gets.to_i
graph = Array.new(N) { [] }
sum = 0
(N - 1).times do
  a, b = gets.split.map(&:to_i)
  sum += 1
  graph[a - 1] << [b - 1, 1]
  graph[b - 1] << [a - 1, 1]
end

dfs = ->(start) {
  visited = Array.new(N, false)
  visited[start] = true
  dist = Array.new(N, nil)
  dist[start] = 0
  stack = [start]
  while (u = stack.pop)
    graph[u].each do |v, c|
      next if visited[v]
      visited[v] = true
      dist[v] = dist[u] + c
      stack << v
    end
  end
  dist
}

d1 = dfs[0]
max = d1.max
v = d1.index(max)
d2 = dfs[v]
diameter = d2.max

puts sum * 2 - diameter