//#include<cstdio>
//#include<cassert>
//#include<iostream>
//#include<cstring>
//#include<algorithm>
#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define MAX ((int)2e9 + 5)
#define MAXP ((int)1e5 + 5)
#define MAXL ((ll)1e18 + 5)
#define MAX_X ((int)2001)
#define MAX_Y ((int)2001)
#define pi acos(-1)
//#define MOD ((int)1e9 + 7)
#define MOD ((int)998244353 + 0)
#define BAS ((int)1e6 + 3)
//#define BAS ((int)2e5 + 3)
#define N ((int)2e5 + 9)
#define eps (1e-8)
#define fastio ios_base::sync_with_stdio(false),cin.tie(NULL)
#define logn 17
#define endl "\n"
#define mpp make_pair
#define BUCK 105
#define LEF (idx<<1)
#define RIG ((idx<<1)|1)
//#define int ll


using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef unsigned long long ull;

/*fast io
ios_base::sync_with_stdio(false);
cin.tie(NULL);
*/




typedef tree < int,  null_type,  less < int >,  rb_tree_tag,  tree_order_statistics_node_update > o_set;
typedef tree < pair < int, int >,  null_type,  less < pair < int, int > >,  rb_tree_tag,  tree_order_statistics_node_update > o_setp;
/// o_set s;
/// s.order_of_key(k) : Number of items strictly smaller than k .
/// *(s.find_by_order(k)) : K-th element in a set (counting from zero).

typedef long double ldd;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int my_rand(int l, int r)
{
    return uniform_int_distribution<int>(l,r) (rng);
}


pair < int , int > dfs(int n , int p) /// returns ( dis , node ) ; node is the farthest from n , dis = distance(node , n)
{
    pair < int , int > ans = {0,n};
    for(auto nxt:vec[n]){
        if(nxt.first != p){
            pair < int , int > tmp = dfs(nxt.first , n);
            tmp.first += nxt.second;
            ans = max(ans , tmp);
        }
    }
    return ans;
}


int main()
{

    pair < int , int > dia = dfs(1,0);
    int a = dia.second;
    dia = dfs(a,0);
    int b = dia.second;
    return 0;
}