#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream cin("darb.in");
ofstream cout("darb.out");
const int NMAX = 100005;
vector<int>lista[NMAX];
queue<int>q;
int dist[NMAX];
int n;

void bfs(int nod){
    for(int i=1;i<=n;i++)
        dist[i] = 0;
    dist[nod] = 1;
    q.push(nod);
    while(!q.empty()){
        int elem;
        elem = q.front();
        q.pop();
        for(int y : lista[elem])
            if(!dist[y]){
                q.push(y);
                dist[y] = dist[elem] + 1;
            }
    }
}

int main(){
    cin >> n;
    for(int i=1;i<=n;i++){
        int x, y;
        cin >> x >> y;
        lista[x].push_back(y);
        lista[y].push_back(x);
    }
    bfs(1);
    int maxi = -1;
    int nodmax;
    for(int i=1;i<=n;i++){
        if(dist[i] > maxi){
            maxi = dist[i];
            nodmax = i;
        }
    }
    bfs(nodmax);
    int lung = 0;
    for(int i=1;i<=n;i++)
        if(lung < dist[i])
            lung = dist[i];
    cout << lung + 1;
    return 0;
}