//
#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<ll, P>IP;
typedef vector<ll> V;
typedef vector<V> V2;
typedef vector<vector<P> > G;
void g_dir(G &graph, ll a, ll b, ll w = 1){graph[a].push_back(P(b, w));}
void g_undir(G &graph, ll a, ll b, ll w = 1){g_dir(graph, a, b, w);g_dir(graph, b, a, w);}
#define rep(i, n) for(ll (i) = 0; (i) < (n); (i)++)
#define rep1(i, n) for(ll (i) = 1; (i) <= (n); (i)++)
#define rrep(i, n) for(ll (i) = (n) - 1; (i) >= 0; (i)--)
#define rrep1(i, n) for(ll (i) = (n); (i) >= 1; (i)--)
template<class T> void chmax(T &a, const T &b){if(a < b){a = b;}}
template<class T> void chmin(T &a, const T &b){if(a > b){a = b;}}
const ll INF = 1145141919;
const ll MOD = 1000000007;
const ll NUM = 101010;

V path[101010];
ll dep[101010];
ll N;
void bfs(ll rt){
    rep1(i, N)dep[i] = INF;
    queue<ll>Q;
    Q.push(rt);
    dep[rt] = 0;
    while(!Q.empty()){
        ll idx = Q.front();
        Q.pop();
        for(auto to : path[idx]){
            if(dep[to] == INF){
                dep[to] = dep[idx] + 1;
                Q.push(to);
            }
        }
    }
}


int main(){

    cin >> N;
    rep(i, N - 1){
        ll a, b;
        cin >> a >> b;
        path[a].push_back(b);
        path[b].push_back(a);
    }
    bfs(1);
    ll nxt = 1;
    rep1(i, N)if(dep[i] > dep[nxt])nxt = i;
    bfs(nxt);
    ll tmp = 0;
    rep1(i, N)chmax(tmp, dep[i]);
    cout << N - 1 - tmp << endl;

    

    return 0;
}