abc7c.java

import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Deque;
import java.util.Scanner;
 
public class Main {
	public static int[][] maze =new int [100][];
	public static int[][] dist =new int [100][];
	public static int[][] dir  ={{-1,0},{1,0},{0,-1},{0,1}};
	public static void main(String[] args) {
		for(int i=0;i<100;i++){
			maze[i]=new int[100];
		}
		for(int i=0;i<100;i++){
			dist[i]=new int[100];
			Arrays.fill(dist[i], -1);
		}
		Deque<int[]> queue=new ArrayDeque<>();
		Scanner sc=new Scanner(System.in);
		int R=sc.nextInt();
		int C=sc.nextInt();
		int sy=sc.nextInt();
		int sx=sc.nextInt();
		int gy=sc.nextInt();
		int gx=sc.nextInt();
		for(int i=1;i<=R;i++){
			String tmp=sc.next();
			for(int j=1;j<=C;j++){
				maze[i][j]=tmp.codePointAt(j-1);
			}
		}
		int[] S={sy,sx};
		queue.add(S);
		maze[sy][sx]=1;//visited
		dist[sy][sx]=0;//start
		int[] now;
		int res=0;
		while(!queue.isEmpty()){
			now=queue.poll();
	//		System.out.println(now[0]+","+now[1]+","+dist[now[0]][now[1]]);
			if((now[0]==gy) && (now[1]==gx)){
				res=dist[now[0]][now[1]];
				break;
			}
			maze[now[0]][now[1]]=1;
			for(int i=0;i<4;i++){
				int newY=now[0]+dir[i][0];
				int newX=now[1]+dir[i][1];
				if(maze[newY][newX]=='.'){	//まだなら，そこに訪れる
					queue.add(new int[]{newY,newX});
					maze[newY][newX]=1;
					dist[newY][newX]=dist[now[0]][now[1]]+1;
				}
			}
 
		}
		System.out.println(res);
		sc.close();
	}
 
}