from collections import deque

N = int( input())
E = [ [] for _ in range(N)]
for _ in range(N-1):
    a, b = map( int, input().split())
    a, b = a-1, b-1
    E[a].append(b)
    E[b].append(a)
s = 0
V = [-1]*N
V[s] = 0
d = deque()
for t in E[s]:
    d.append(t)
    V[t] = 1
while d:
    t = d.popleft()
    l = V[t]
    for u in E[t]:
        if V[u] == -1:
            V[u] = l+1
s = V.index( max(V))
V = [-1]*N
V[s] = 0
d = deque()
for t in E[s]:
    d.append(t)
    V[t] = 1
while d:
    t = d.popleft()
    l = V[t]
    for u in E[t]:
        if V[u] == -1:
            V[u] = l+1
print( N - 1 - max(V))