#include<bits/stdc++.h>
using namespace std;
int N,x,y,Max1,Max2;
bool viz[100001];
vector <int> G[100001];
void dfs(int nod,int nr){
    viz[nod]=1;
    if(nr>Max1)Max2=Max1,Max1=nr;
    for(int i=0;i<G[nod].size();++i)
        if(!viz[G[nod][i]])
            dfs(G[nod][i],nr+1);
}
int main()
{
    freopen("darb.in","r",stdin);
    freopen("darb.out","w",stdout);
    scanf("%d",&N);
    while(N--){
        scanf("%d%d",&x,&y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
    dfs(1,0);
    Max1+=Max2+1;
    printf("%d",Max1);
    return 0;
}