array list로 구현한 graph

package ch6;
import java.util.*;
//list 로 graph 구현 
/*
* 예제입력 
* 4 5 1	정점의수, 간선의수, 탐색을 시작할번호 
	1 2
	1 3
	1 4
	2 4
	3 4
*/

public class graph_list {
	public static void Main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n= scan.nextInt();
		ArrayList<Integer>[] a = (ArrayList<Integer>[]) new ArrayList[n+1];
		for(int i=1;i<n+1;i++) {
			a[i] = new ArrayList<>();
		}
		int num = scan.nextInt();
		int start = scan.nextInt();
		
		for(int i=0;i<num; i++) {
			int v=scan.nextInt();
			int w=scan.nextInt();
			a[v].add(w);
			a[w].add(v);
			
		}
		
	
		
	}

}