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

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);
    maxi = -1;
    for(int i=1;i<=n;i++)
        maxi = max(maxi, dist[i]);
    cout << maxi + 1;
    return 0;
}