#include <bits/stdc++.h>

using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
int N,sol,dp[100005];
vector < int > L[100005];

inline void Read()
{
    int i,x,y;
    fin>>N;
    for(i = 1; i < N; i++)
    {
        fin >> x >> y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
}

inline void DFS(int nod, int tata)
{
    int i,j,max1,max2,Nnod;
    max1 = max2 = 0;
    for(i = 0; i < L[nod].size(); i++)
    {
        Nnod = L[nod][i];
        if(Nnod == tata) continue;
        DFS(Nnod,nod);
        if(dp[Nnod] > max1) max2 = max1, max1 = dp[Nnod];
        else if(dp[Nnod] > max2) max2 = dp[Nnod];
    }
    dp[nod] = max1 + 1;
    sol = max(sol, max1 + max2 + 1);
}

int main()
{
    Read();
    DFS(1,0);
    fout << sol << "\n";
    fout.close();
    return 0;
}