#include <bits/stdc++.h>
using namespace std;
pair<int,int> bfs(int src, int n, vector<vector<int>>& adj) {
    vector<int> d(n+1,-1); queue<int> q;
    q.push(src); d[src]=0; int far=src;
    while (!q.empty()) {
        int u=q.front(); q.pop();
        if (d[u]>d[far]) far=u;
        for (int v:adj[u]) if (d[v]==-1) { d[v]=d[u]+1; q.push(v); }
    }
    return {far,d[far]};
}
int main() {
    int n; cin>>n;
    vector<vector<int>> adj(n+1);
    for (int i=0;i<n-1;i++) {
        int u,v; cin>>u>>v; adj[u].push_back(v); adj[v].push_back(u);
    }
    auto [a,d1]=bfs(1,n,adj);
    auto [b,diam]=bfs(a,n,adj);
    cout<<diam<<"\n";
}