#include <iostream>
#include <vector>
#include <queue>
#include <cstdio>
#include <cstring>

#define NMax 100005
using namespace std;

vector<int> G[NMax];
queue<int> q;
int n,x,y,timp,mx,ultim;
int viz[NMax];

int main()
{
    freopen("darb.in","r",stdin);
    freopen("darb.out","w",stdout);
    scanf("%d",&n);
    for(int i = 1; i <= n; ++i){
        scanf("%d%d",&x,&y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
    q.push(1);
    while(!q.empty()){
        int nod = q.front();
        q.pop();
        for(int i = 0 ; i < G[nod].size(); ++i){
            if(!viz[G[nod][i]]){
                viz[G[nod][i]] = 1;
                ultim = G[nod][i];
                q.push(G[nod][i]);
            }
        }
    }
    memset(viz,0,sizeof(viz));
    q.push(ultim);
    viz[ultim] = 1;
    while(!q.empty()){
        int nod = q.front();
        q.pop();
        for(int i = 0 ; i < G[nod].size(); ++i){
            if(!viz[G[nod][i]]){
                viz[G[nod][i]] = viz[nod] + 1;
                if(viz[G[nod][i]] > mx)
                    mx = viz[G[nod][i]];
                q.push(G[nod][i]);
            }
        }
    }
    printf("%d\n",mx);
    return 0;
}