import sys
sys.setrecursionlimit(10**8)
def one_str():
    return input()

def many_int():
    return list(map(int, input().split()))

from collections import deque

input_count = 0
N  = many_int()[0]

G = {i+1:[] for i in range(N)}

for i in range(N-1):
    x,y = many_int()
    G[x].append(y)
    G[y].append(x)
    
dim_num = {k:len(v)-1 for k, v in G.items()}
new_G = {}
for k, v in G.items():
    if (len(v) == 1) and k!=1:
        new_G[k] = []
    else:
        new_G[k] = v
G = new_G

G

new_G

reached = set([])
def dfs(node, old_node):
    global G
    reached.add(f"{node}_{old_node}")
    reached.add(f"{old_node}_{node}")
    
    temp_deq = deque([])
    now_dim = max(dim_num[node]-2, 0)
    if now_dim > 0:
        temp_deq.append([node, now_dim])
    
    for next_node in G[node]:
        if f"{node}_{next_node}" not in reached:
            temp_deq += dfs(next_node, node)
            
    if len(temp_deq)!=0:
        if dim_num[node]==1:
            if temp_deq[0][1]==0:
                temp_deq.popleft()
            temp_deq[0][1]-=1
            dim_num[temp_deq[0][0]] -= 1
            dim_num[node] += 1
            
            n = G[temp_deq[0][0]].pop()
            G[node].append(n)
    return temp_deq



dim_num[1] += 1

dfs(1, -1)

reached = set([])

def dfs2(node, old_node):
    global G
    reached.add(f"{node}_{old_node}")
    reached.add(f"{old_node}_{node}")
    temp = 0
    hoge = []
    for next_node in G[node]:
        if f"{node}_{next_node}" not in reached:
            hoge.append(dfs2(next_node, node))
            
    return sum(sorted(hoge, reverse=True)[:2])+1

print(dfs2(1, -1))