//考完试才做出来，自己写了几个例子试了一下是对的，不知道有没有更高效的思路
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;
import java.util.Set;

public class Main {
    static class Result{
        int back;
        int notback;
        public Result(int back,int notback){
            this.back = back;
            this.notback = notback;
        }
    }

    static class Pair{
        int p1,p2;
        public boolean contains(int s){
            return p1==s||p2==s;
        }
        public Pair(int p1,int p2){
            this.p1 = p1;
            this.p2 = p2;
        }
        public int another(int p){
            if (p==p1){
                return p2;
            }else return p1;
        }
    }
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        s.nextLine();
        Set<Pair> pool = new HashSet<Pair>();
        for (int i=0;i<n-1;i++){
            String[] temp = s.nextLine().split(" ");
            pool.add(new Pair(Integer.parseInt(temp[0]),Integer.parseInt(temp[1])));
        }
        //System.out.println(pool.size());
        System.out.println(func(1,pool).notback);


    }
    private static Result func(int i, Set<Pair> pool) {

        Set<Pair> connted = connected(pool,i);
        if (connted.size()==0){
            //System.out.println(i+","+"0,0");
            return new Result(0,0);
        }
        pool.removeAll(connted);
        int m =0,n=0;
        List<Result> results = new ArrayList<Result>();
        for (Pair p:connted){
            int v = p.another(i);
            Result r = func(v,pool);
            results.add(r);
        }
        int max = 0;
        for (Result result:results){
            m += result.back + 2;
            if (result.back-result.notback>max){
                max = result.back-result.notback;
            }
        }
        n = m -max -1;
        //System.out.println(i+","+m+","+n);
        return new Result(m,n);
    }

    private static Set<Pair> connected(Set<Pair> pool,int target){
        Set<Pair> ret = new HashSet<Pair>();
        for (Pair p:pool){
            if (p.contains(target)){
                ret.add(p);
            }
        }
        return ret;

    }

}

创作者周榜