#include<bits/stdc++.h>
using namespace std;
ifstream F("darb.in");
ofstream G("darb.out");
vector<int> v[100001];
int i,j,s;
bool c[100001],t;
void A(int i,int l)
{
    if(c[i]=t,l>s)
        s=l,j=i;
    for(int j:v[i])
        if(c[j]!=t)
            A(j,l+1);
}
int main()
{
    for(F>>i;F>>i>>j;v[i].push_back(j),v[j].push_back(i));
    return t=1,A(1,1),t=0,A(j,1),G<<s,0;
}