# your code goes here
import sys
sys.setrecursionlimit(100000)
 
def dfs(node, parent, depth, adj):
    global max_depth, farthest_node
    if depth > max_depth:
        max_depth = depth
        farthest_node = node
    for neighbor in adj[node]:
        if neighbor != parent:
            dfs(neighbor, node, depth + 1, adj)
 
def longest_path_in_tree(n, edges):
    adj = [[] for _ in range(n + 1)]
    for u, v in edges:
        adj[u].append(v)
        adj[v].append(u)
 
    # First DFS
    global max_depth, farthest_node
    max_depth = -1
    farthest_node = 1
    dfs(1, -1, 0, adj)
 
    # Second DFS from the farthest node found
    max_depth = -1
    dfs(farthest_node, -1, 0, adj)
 
    return max_depth
 
# Input parsing
n = int(input())
edges = [tuple(map(int, input().split())) for _ in range(n - 1)]
print(longest_path_in_tree(n, edges))
 

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