#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

#define INF 1000000021
#define MOD 1000000007
#define pb push_back
#define sqr(a) (a)*(a)
#define M(a, b) make_pair(a,b)
#define F first
#define S second
#define all(x) (x.begin(), x.end())
#define deb(x) cerr << #x << " = " << x << '\n'
#define N 222222

using namespace std;
using namespace __gnu_pbds;

typedef long double ld;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> indexed_set;

const ld pi = 2 * acos(0.0);
template<class T> bool umin(T& a, T b){if(a>b){a=b;return 1;}return 0;}
template<class T> bool umax(T& a, T b){if(a<b){a=b;return 1;}return 0;}
template<class T, class TT> bool pal(T a, TT n){int k=0;for(int i=0;i<=n/2;i++){if(a[i]!=a[n-i-1]){k=1;break;}}return k?0:1;}

//int month[] = {0,31,28,31,30,31,30,31,31,30,31,30,31};

int a[N], s[N], w[N];
vi v[N];

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	freopen("darb.in", "r", stdin);
	freopen("darb.out", "w", stdout);
	int n;
	cin >> n;
	for(int i = 1; i < n; i ++)
	{
		int x, y;
		cin >> x >> y;
		v[x].pb(y);
		v[y].pb(x);
	}
	int ans = 0;
	function<void(int, int)> dfs = [&](int u, int e)
	{
		vi f;
		int t = 0;
 		for(auto it : v[u])
 		{
 			if(it == e)
 				continue;
 			dfs(it, u);
 			umax(w[u], w[it]+1);
 			f.pb(w[it]);
 			t ++;
 		}
 		if(!t)
 			w[u] = 1;
 		int m1 = 0, m2 = 0, cnt = 0;
 		for(auto it : f)
 			umax(m1, it);
 		for(auto it : f)
 			cnt += (m1 == it);
 		for(auto it : f)
 			if(m1 != it)
 				umax(m2, it);
 		if(cnt > 1)
 			m2 = m1;
 		umax(ans, m1 + m2);
	};
	
	dfs(1, 0);
	cout << ans+1;
	getchar();
	getchar();
	return 0;
}