import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 6)
if "pypyjit" in sys.builtin_module_names:
    import pypyjit
    pypyjit.set_param("max_unroll_recursion=-1")

N=int(input())
edge = [[] for _ in range(N)]
XY=[list(map(int,input().split())) for _ in range(N-1)]
for x,y in XY:
    x,y=x-1,y-1
    edge[x].append(y)
    edge[y].append(x)
visit = [0]*N

dnode = []
from heapq import *

def dfs(v=0):
    visit[v]=1
    n_tree = []
    del_lst = []
    for to in edge[v]:
        if visit[to]:continue
        n,lst = dfs(to)
        n_tree.append(n)
        del_lst.extend(lst)
    if len(n_tree)==0:
        return 1,[]
    if len(n_tree)==1:
        if del_lst:
            # heapify(del_lst)
            n = -heappop(del_lst)
        else: n=0
        return n+n_tree[0]+1,del_lst
    if len(n_tree)<=2:
        return sum(n_tree)+1,del_lst
    # n_tree.sort(reverse=True) # 重い
    mx1,mx2=0,0
    for n in n_tree:
        if mx1<n:
            mx2=mx1
            mx1=n
        elif mx2<n:
            mx2=n
    ret = mx1+mx2+1
    for i in n_tree:
        if i!=mx1:
            if i!=mx2:
                heappush(del_lst, -i)
            else:mx2=-1
        else:mx1=-1
    return ret,del_lst

ans,dl = dfs()
print(ans)