#include<bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
#define dis(a,b) abs(a-b)
using namespace std;
char maze[1001][1001];
int l[1001][1001];
struct pos
{
	int x,y;
	int distance=-1;
};
struct cmp
{
    bool operator()(pos a,pos b)
    {
    //	return 0;
    	int k=a.distance+l[a.x][a.y],k2=b.distance+l[b.x][b.y];
    	if(k!=k2)return k>k2;
    	return l[a.x][a.y]>l[b.x][b.y];
    	//return<;
    }
} ;

void astar(int x,int y,int tx,int ty,int t)
{
	int move[4][2]={{0,1},{0,-1},{1,0},{-1,0}};
	if(maze[x][y]=='X'||maze[tx][ty]=='X')
	{
		cout<<"ERROR\n";
		return;
	}
	l[x][y]=1;
	pos p;
	p.x=x;
	p.y=y;
	p.distance=dis(x,tx)+dis(y,ty);
	priority_queue<pos,vector<pos>,cmp> pq;
	pq.push(p);
	while(!pq.empty())
	{
		p=pq.top();
		if(l[tx][ty]) break;
		int k=l[p.x][p.y];
		pq.pop();
		rep(i,4)
		{
			pos p2;
			int x2=p.x+move[i][0];
			int y2=p.y+move[i][1];
			if(x2>=0&&x2<t&&y2>=0&&y2<t)
			{
				if(!l[x2][y2]&&maze[x2][y2]!='X')
				{
					l[x2][y2]=k+1;
					p2.x=x2;
					p2.y=y2;
					p2.distance=dis(tx,x2)+dis(ty,y2);
					pq.push(p2);
				}
			}

		}
	/*	rep(i,t)
		{
			rep(j,t)
			{
				cout<<setw(4)<<l[i][j]<<" ";
			}
			cout<<"\n";
		}
		cout<<"\n";
		system("pause");*/
	}

	cout<<l[tx][ty]-1<<"\n";
	return;
}
int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n,m;
	cin>>n>>m;
	rep(i,n)
	rep(j,n) cin>>maze[i][j];
	while(m--)
	{
		memset(l,0,sizeof(l));
		int x,y,x2,y2;
		cin>>x>>y>>x2>>y2;
		astar(x,y,x2,y2,n);
	}
}