#include <cstdio>
#include <queue>

using namespace std;
int n,i,x,y,ult,distmax;
bool viz[100005],viz2[100005];

queue <int> q;
vector <int> v[100005];

void bfs(int x)
{
    viz[x]=1;
    ult=x;
    q.push(x);
    while (!q.empty())
    {
        x=q.front();
        q.pop();
        int lungime=v[x].size();
        for (int i=0; i<lungime; i++)
            if (viz[v[x][i]]==0)
            {
                ult=v[x][i];
                q.push(v[x][i]);
                viz[v[x][i]]=1;
            }
    }
}

void dfs(int x, int dist)
{
    if (dist>distmax) distmax=dist;
        viz2[x]=1;
    int lungime=v[x].size();
    for (int i=0; i<lungime; i++)
        if (viz2[v[x][i]]==0)
        dfs(v[x][i],dist+1);
}

int main()
{
    freopen("darb.in","r",stdin);
    freopen("darb.out","w",stdout);
    scanf("%d",&n);
    for (i=1; i<=n; i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    bfs(1);
    dfs(ult,1);
    printf("%d\n",distmax);
    return 0;
}