from collections import deque

def bfs(v):
    T=[-1]*(N+1)
    T[v]=0
    Q=deque([v])

    while Q:
        w=Q.popleft()
        for u in E[w]:
            if T[u]==-1:
                T[u]=T[w]+1
                Q.append(u)

    x=max(range(1,N+1),key=lambda x:T[x])
    return x,T[x]

N=int(input())
E=[set() for _ in range(N+1)]

for _ in range(N-1):
    a,b=map(int,input().split())
    E[a].add(b)
    E[b].add(a)

u,_=bfs(1)
_,d=bfs(u)

print((N-1)-d)