import sys
sys.setrecursionlimit(10**6)

N = int(input())
ab = [list(map(int, input().split())) for _ in range(N-1)]

G = [[] for _ in range(N)]
for i in range(N-1):
    a, b = ab[i]
    a -= 1
    b -= 1
    G[a].append(b)
    G[b].append(a)

def dfs(now, prev):
    for nxt in G[now]:
        if nxt == prev:
            continue
        dist[nxt] = dist[now] + 1
        dfs(nxt, now)
        
dist = [float('inf')] * N
dist[0] = 0
dfs(0, -1)
idx = dist.index(max(dist))
dist = [float('inf')] * N
dist[idx] = 0
dfs(idx, -1)
ans = N-1-max(dist)
print(ans)