#include<bits/stdc++.h>
#define N 100100

using namespace std;

queue<int>Q;
int n;
vector<int>V[N];
int viz[N];
int last, s;

void BFS(int x) {
    Q.push(x); viz[x]=1;
    while (Q.size()) {
        x=Q.front(); Q.pop();
        last=x;
        for (auto it:V[x]) {
            if (!viz[it]) {
                Q.push(it);
                viz[it]=viz[x]+1;
            }
        }
    }
}

int main() {
    ifstream cin("darb.in");
    ofstream cout("darb.out");
    cin>>n;

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

    BFS(1);
    for (int i=1; i<=n; i++) viz[i]=0;
    BFS(last);
    cout<<viz[last];

    return 0;
}