from collections import deque
N = int(input())
G = {i:[] for i in range(1,N+1)}
for _ in range(N-1):
    a,b = map(int,input().split())
    G[a].append(b)
    G[b].append(a)
d1 = [-1 for _ in range(N+1)]
d1[1] = 0
que = deque([(1,d)])
while que:
    x,d = que.popleft()
    for y in G[x]:
        if d1[y]<0:
            d1[y]=d+1
            que.append((y,d+1))
dmax = 0
for i in range(1,N+1):
    if dmax<d1[i]:
        dmax = d1[i]
        ind = i
d2 = [-1 for _ in range(N+1)]
d2[ind]=0
que = deque([(ind,0)])
while que:
    x,d = que.popleft()
    for y in G[x]:
        if d2[y]<0:
            d2[y]=d+1
            que.append((y,d+1))
dmax = max(d2)
print(N-1-dmax)