lca.py

import sys
sys.setrecursionlimit(int(1e5)) #노드 깊이 10000까지
n = int(input())

parent = [0] * (n + 1)
d = [0] * (n + 1)
c = [0] * (n + 1)
graph = [[] for _ in range(n + 1)]

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

def dfs(x, depth):
    c[x] = True
    d[x] = depth
    for y in graph[x]:
        if c[y]:
            continue
        parent[y] = x
        dfs(y, depth + 1)

def lca(a, b):
    while d[a] != d[b]:
        if d[a] > d[b]:
            a = parent[a]
        else:
            b = parent[b]
            
    while a != b:
        a = parent[a]
        b = parent[b]

    return a

dfs(1, 0)

# m = int(input())

# for i in range(m):
#     a, b = map(int, input().split())
#     print(lca(a, b))

a, b = map(int, input().split())
print(lca(a, b))