#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <vector>
#define N 101010


using namespace std;

int grad[N],dist[N];
int que[N],head,tail;

void push(int x){
    que[head++]=x;
}
int pop(){
    return que[tail++];
}

vector <int> muc[N];

void bfs(int k){
    static int vec,i;

    head=tail=0;
    push(k);
    dist[k]=1;
    while (head>tail){

        k=pop();

        for(i=0;i<grad[k];i++){
            vec=muc[k][i];
            if(dist[vec]==0){
                dist[vec]=dist[k]+1;
                push(vec);
            }
        }

    }

}

int main(){
    int n,i,x,y;


    freopen("darb.in","r",stdin);
    freopen("darb.out","w",stdout);

    scanf("%d",&n);

    for(i=0;i<n-1;i++){
        scanf("%d%d",&x,&y);
        muc[x].push_back(y);
        muc[y].push_back(x);
        grad[x]++;
        grad[y]++;
    }

    bfs(1);

    x=0;
    for(i=1;i<=n;i++){
        if(dist[i]>x){
            x=dist[i];
            y=i;
        }

    }

    memset(dist,0,(n+1)*sizeof(int)  );

    bfs(y);
    x=0;

    for(i=1;i<=n;i++){
        if(dist[i]>x){
            x=dist[i];
        }

    }
    printf("%d",x);
    return 0;
}