from collections import deque
N = int(input())
G = [list() for _ in range(N)]
for i in range(N - 1):
    u, v = map(int, input().split())
    u -= 1
    v -= 1
    G[u].append(v)
    G[v].append(u)

# 木の直径を求める
dist0 = [-1] * N
dist0[0] = 0
que = deque([0])
while que:
    pos = que.popleft()
    for nex in G[pos]:
        if dist0[nex] == -1:
            dist0[nex] = dist0[pos] + 1
            que.append(nex)
# 0 から一番遠い点uは？
u = dist0.index(max(dist0))
# u から BFS
distu = [-1] * N
distu[u] = 0
que = deque([u])
while que:
    pos = que.popleft()
    for nex in G[pos]:
        if distu[nex] == -1:
            distu[nex] = distu[pos] + 1
            que.append(nex)
v = distu.index(max(distu))
diameter = distu[v]
ans = N - 1 + (N - diameter - 1)
print(ans)