N = int(input())

V = [[] for _ in range(N)]

for _ in range(N-1):
    a, b = map(int, input().split())
    V[a-1].append(b-1)
    V[b-1].append(a-1)
    
def dfs(prev, i, n):
    stack = [(prev, i, n)]
    ans = (-1, -1)
    while len(stack) > 0:
        prev, i, n = stack.pop()
        if len(V[i]) == 1 and V[i][0] == prev:
            ans = max(ans, (n, i))
        else:
            for j in V[i]:
                if j != prev:
                    stack.append((i, j, n+1))
    return ans

n, u= dfs(-1, 0, 0)
n, v = dfs(-1, u, 0)

print(2*(N-1)-n)