#include <bits/stdc++.h>
#pragma GCC optimize ("Ofast")

using namespace std;

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

const int MAX_N = 100005;
int n, x, y, far, maxx;
vector <int> edge[MAX_N];

bool viz[MAX_N];
void dfs(int crt, int len){
    if(len > maxx){
        maxx = len;
        far = crt;
    }

    if(len == 1)
        for(int i=1; i<=n; i++)
            viz[i] = false;

    viz[crt] = true;
    for(auto nxt : edge[crt])
        if(viz[nxt] == false)
            dfs(nxt, len+1);
}

int main (){
    ios_base::sync_with_stdio(false);
    fin.tie(nullptr), fout.tie(nullptr);

    fin>>n;
    for(int i=1; i<=n; i++){
        fin>>x>>y;
        edge[x].push_back(y);
        edge[y].push_back(x);
    }

    dfs(1, 1);
    dfs(far, 1);
    fout<<maxx;
    return 0;
}