[백준] 26069번 붙임성 좋은 총총이 (silver 4

import java.io.*;
import java.util.*;
public class Main{
    public static void main(String[] args)throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st;
        HashMap<String, Integer> map=new HashMap<>();
        int n=Integer.parseInt(br.readLine());
        map.put("ChongChong",1);
        for(int i=0; i<n; i++){
            st=new StringTokenizer(br.readLine());
            String name=st.nextToken();
            String meet=st.nextToken();
            if(map.get(name)!=null){
                map.put(meet,1);
            }
            else if(map.get(meet)!=null){
                map.put(name,1);
            }
        }
        bw.write(map.size()+"");
        bw.flush();
    }
}