n = int(input())
G = [[] for _ in range(n)]
for _ in range(n - 1):
    a,b = map(int,input().split())
    a -= 1
    b -= 1
    G[a].append(b)
    G[b].append(a)

def max_depth(s):
    ans = 0
    idx = 0
    depth = [-1] * n
    depth[s] = 0
    stack = [s]
    while stack:
        p = stack.pop()
        for v in G[p]:
            if  depth[v] >= 0:
                continue
            depth[v] = depth[p] + 1
            if ans < depth[v]:
                ans = depth[v]
                idx = v
            stack.append(v)

    return ans,idx

depth,s = max_depth(0)
max_dep,i = max_depth(s)
print(n - max_dep - 1)