C++ :

#include<iostream>
using namespace std;
int n,x1,x2,y1,y2,h=0,r=1;;
char a[1001][1001];
int b[1000000][4],c[1001][1001]={0};
int dx[]={0,0,1,-1},dy[]={1,-1,0,0};
void bfs();
int main()
{
	cin>>n;
	for(int i=1;i<=n;++i)
	for(int j=1;j<=n;++j)
	cin>>a[i][j];
	cin>>x1>>y1>>x2>>y2;
	bfs();
	return 0;
	
}
void bfs()
{
	int x,y;
	b[1][1]=x1;
	b[1][2]=y1;
	b[1][3]=0;
	c[x1][y1]=1;
	while(h<r)
	{
		++h;
		for(int i=0;i<4;++i)
		{
			x=b[h][1]+dx[i];
			y=b[h][2]+dy[i];
			if(x>0&&x<=n&&y>0&&y<=n&&!c[x][y]&&a[x][y]=='0')
			{
				c[x][y]=1;
				++r;
				b[r][1]=x;
				b[r][2]=y;
				b[r][3]=b[h][3]+1;
			}
			if(x==x2&&y==y2)
			{
				cout<<b[r][3];
				return;
			}
		}
	}
}

Pascal :

const maxn=1000;
dx:array[1..4] of longint=(0,1,0,-1);
dy:array[1..4] of longint=(1,0,-1,0);
var x1,y1,x2,y2,n,i,j,fp,rp:longint;
ch:char;
a:array[1..maxn,1..maxn] of record
num,road:longint;
end;
q:array[1..maxn*maxn] of record
x,y,route:longint;
end; procedure search(i,j:integer);
var k:longint;
begin
q[1].x:=x1; q[1].y:=y1; q[1].route:=0;
fp:=1; rp:=1;
repeat
for k:=1 to 4 do
if (q[fp].x+dx[k]>=1) and (q[fp].x+dx[k]<=n) and (q[fp].y+dy[k]>=1)
and (q[fp].y+dy[k]<=n) and (a[q[fp].x+dx[k],q[fp].y+dy[k]].num=0) then
begin
inc(rp);
q[rp].x:=q[fp].x+dx[k];
q[rp].y:=q[fp].y+dy[k];
q[rp].route:=q[fp].route+1;
a[q[rp].x,q[rp].y].road:=q[rp].route;
a[q[rp].x,q[rp].y].num:=1;
end;
inc(fp);
until fp>rp;
end; begin
readln(n);
for i:=1 to n do
begin
for j:=1 to n do
begin
read(ch);
a[i,j].num:=ord(ch)-ord('0');
end;
readln;
end;
readln(x1,y1,x2,y2);
search(x1,y1);
writeln(a[x2,y2].road);
end.