#include <fstream>
#include <vector>
#include <queue>
#include <string.h>

using namespace std;

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

const int MaxN = 100005;

int N;
vector<int> G[MaxN];
int cnt[MaxN], last, diametru;
bool v[MaxN];
queue<int> Q;

void Read();
void BFS(int x);

int main()
{
    Read();
    BFS(1);
    BFS(last);

    fout <<diametru;

    return 0;
}

void Read()
{
    fin >> N;
    while(N--)
    {
        int x, y;
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }

    fin.close();
}
void BFS(int x)
{
    memset(cnt, 0, MaxN);
    memset(v, false, MaxN);

    Q.push(x);
    cnt[x] = 1;
    v[x] = true;

    while(!Q.empty())
    {
        int newx = Q.front();
        Q.pop();
        for(const int& y : G[newx])
            if(!v[y])
        {
            Q.push(y);
            cnt[y] = cnt[newx] + 1;
            v[y] = true;

            diametru = cnt[y];
            last =  y;
        }
    }
}