#include <bits/stdc++.h>

using namespace std;

ifstream fin("darb.in");
ofstream fout("darb.out");

const int NMax = 1e5 + 5;

int last;
int D[NMax];

vector < int > G[NMax];
list < int > Q;

inline void BFS(const int &start){
    int node;
    Q.push_back(start);
    memset(D, 0, sizeof(D));
    D[start] = 1;
    while(!Q.empty()){
        node = Q.front(); Q.pop_front();
        last = node;
        for(auto it: G[node]){
            if(D[it] == 0){
                D[it] = D[node] + 1;
                Q.push_back(it);
            }
        }
    }
}

int main(){
    int n, x, y;
    fin >> n;
    for(int i = 1; i <= n; i++){
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    BFS(1);
    BFS(last);
    fout << D[last];
    return 0;
}