/*****************************************
Note  : 
******************************************/
#include <queue>
#include <math.h>
#include <stack>
#include <stdio.h>
#include <iostream>
#include <vector>
#include <iomanip>
#include <string.h>
#include <algorithm>
using namespace std;
#define LL long long
const int N = 100;
const int INF = 0x3f3f3f3f;
int n , m;
int sx,sy,ex,ey;
char a[N][N]; 
int st[N][N];
struct node
{
	int x,y,step;
	bool operator < (const node & a)const 
	{
		return step > a.step;
	}
};
int dx[] = {1,-1,0,0};
int dy[] = {0,0,1,-1};
bool flag(int x,int y)
{
	if(x < 0 || y < 0 || x > n || y > m)
		return false;
	return true;
}
int bfs()
{
	priority_queue<node> p;
	p.push((node){sx,sy,0});
	st[sx][sy] = 1;
	while(!p.empty())
	{
		node t = p.top();
		p.pop();
		for(int i = 0 ; i < 4 ; i++)
		{
			int x = dx[i] + t.x;
			int y = dy[i] + t.y;
			if(!flag(x,y))	continue;
			if(x == ex && y == ey )	 return t.step + 1;
			if(a[x][y] == 'X') continue;
			if(st[x][y] <= t.step)	continue;
			st[x][y] = t.step + 1;
			p.push((node){x,y,t.step + 1});
			int xx = x + dx[i];
			int yy = y + dy[i];
			while(flag(xx,yy))
			{
				if(xx == ex && yy == ey)
					return t.step + 1;
				if(a[xx][yy] == 'X') break;
				if(st[xx][yy] <= t.step)
					break;
				st[xx][yy] = t.step + 1;
				p.push((node){xx,yy,t.step + 1});
				xx = xx + dx[i];
				yy = yy + dy[i];
			}

		}
	}

	return -1;
}
int main()
{	
	int t = 0;
	while(cin >> m >> n && n + m)
	{
		memset(a, ' ' , sizeof(a));
		getchar();
		for(int i = 1 ; i <= n ; i++)
			cin.getline(a[i]+ 1, 100);
		n += 1;
		m += 1;
		printf("Board #%d:\n",++t);
		int tt = 0;
		while(cin >> sy >> sx >> ey >> ex && sx + sy + ex + ey )
		{
			memset(st,0x3f ,sizeof(st));
			printf("Pair %d: ",++tt);
			int ans = bfs();
			if(ans < 0) cout << "impossible.\n";
			else cout << ans << " segments.\n";
		}
		cout << endl;
	}
	return 0;
}