#include <bits/stdc++.h>
#define NMAX 100003

using namespace std;

int n,sol;
vector<int>v[NMAX];

int diametrul(int nod,int root){
    int hmax=0,hmax2=0;
    for(int i=0;i<v[nod].size();i++){
        if(v[nod][i]!=root){
            int aux=diametrul(v[nod][i],nod);
            if(hmax<=aux){
                hmax2=hmax;
                hmax=aux;
            }else if(hmax2<aux){
                hmax2=aux;
            }
        }
    }
    sol=max(sol,hmax+hmax2+1);
    return hmax+1;
}

int main()
{
    freopen("darb.in","r",stdin);
    freopen("darb.out","w",stdout);
    scanf("%d",&n);
    for(int i=1;i<=n-1;i++){
        int x,y;
        scanf("%d %d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    diametrul(1,1);
    printf("%d\n",sol );

    return 0;
}