#include<bits/stdc++.h>
#define ll long long

using namespace std;

int main()
{
    ll n,x,y;
    cin >> n;
    vector<ll>g[n+1];
    for(ll i = 0; i<n-1 ; i++){
        cin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    vector<ll>vis(n+1);
    vector<ll>dis(n+1);
    ll src = g[1][0];
    dis[src] = 0;
    vis[src] = 1;
    queue<ll> q;
    q.push(src);
    while(q.size() > 0){
        ll x = q.front();            q.pop();
        for(ll i = 0; i<g[x].size(); i++){
            if(vis[g[x][i]] == 1)continue;
            vis[g[x][i]] = 1;
            dis[g[x][i]] = dis[x] + 1;
            q.push(g[x][i]);

        }
    }
    ll max = -1;
    ll index;

    for(ll i =0 ; i<dis.size(); i++){
        if(dis[i] > max){
            max = dis[i];
            index = i;
        }
    }
        vector<ll>vis1(n+1);
    vector<ll>dis1(n+1);
    src = index;
    dis1[src] = 0;
    vis1[src] = 1;
    queue<ll> q1;
    q1.push(src);
    while(q1.size()){
        ll x = q1.front();
        q1.pop();
        for(ll i = 0; i<g[x].size(); i++){
            if(vis1[g[x][i]] == 1)continue;
            vis1[g[x][i]] = 1;
            dis1[g[x][i]] = dis1[x] + 1;
            q1.push(g[x][i]);
        }
    }
    for(ll i =0 ; i<dis.size(); i++){
        if(dis1[i] > max){
            max = dis1[i];
            index = i;
        }
    }
    cout << max << endl;

    return 0;
}