#include <cstdio>
#include <vector>
#include <cstring>

#define Nmax 100005

using namespace std;
int N;
vector<int> G[Nmax];
int used[Nmax],start,dmax;


void Read()
{
    scanf("%d",&N);
    int a,b;
    for(int i = 1; i <= N; ++i){
        scanf("%d%d",&a,&b);
        G[a].push_back(b);
        G[b].push_back(a);
    }
    start = 1;
}

void DFS(int k,int depth){
    used[k] = 1;
    if(depth > dmax){
        dmax = depth;
        start = k;
    }
    for(vector<int>::iterator it = G[k].begin(); it != G[k].end(); ++it)
        if(!used[*it])
            DFS(*it,depth+1);
}

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

    Read();
    DFS(start,1);
    memset(used,0,sizeof(used));
    DFS(start,1);
    printf("%d\n",dmax);

    return 0;
}