#include<iostream>
#include<fstream>
#include<queue>

using namespace std;

int map[80][80];
int v[80][80];
int move[4][2]={0,1,0,-1,1,0,-1,0};
int n,m,x,y,x0,y0;

struct node{
	int s,t,k,f;
	friend bool operator <(node a,node b){
		return(a.k>b.k);
	}
};

int ok(int s,int t){
	if(s>=0&&s<=n&&t>=0&&t<=m&&map[s][t]==0)
		return(1);
	return(0);
}

int solve(){
	int i,j,k,t,f;
	priority_queue<node> a;
	node b;
	for(i=0;i<4;i++)
	{
		b.s=x+move[i][0];
		b.t=y+move[i][1];
		if(ok(b.s,b.t))
		{
			b.f=i;
			b.k=1;
			a.push(b);
		}
	}

	while(!a.empty())
	{
		b=a.top();
		a.pop();
		i=b.s;
		j=b.t;
		if(i==x0&&j==y0)
		{
			return(b.k);
		}
		k=b.k;
		f=b.f;
		if(v[i][j])
			continue;
		v[i][j]=1;
		for(t=0;t<4;t++)
		{
			i+=move[t][0];
			j+=move[t][1];
			if(v[i][j]==0&&ok(i,j))
			{
				b.s=i;
				b.t=j;
				b.f=t;
				if(b.f==f)
					b.k=k;
				else
					b.k=k+1;
				a.push(b);
			}
			i-=move[t][0];
			j-=move[t][1];
		}
	}
	return(0);

}


int main(){
	//ifstream cin("in.txt");
	int i,j,k,h=0;
	while(1){
		cin>>m>>n;
		h++;
		if(n==0&&m==0)
			return(0);
		memset(map,0,sizeof(map));
		for(i=1;i<=n;i++)
		{
			cin.get();
			for(j=1;j<=m;j++)
			{
				if(cin.get()=='X')
					map[i][j]=1;
			}
		}
		n++;
		m++;
		cout<<"Board #"<<h<<":"<<endl;
		i=0;
		while(1)
		{
			i++;
			cin>>y>>x>>y0>>x0;
			j=map[x0][y0];
			map[x0][y0]=0;
			if(y==0)
				break;
			memset(v,0,sizeof(v));
			k=solve();
			map[x0][y0]=j;
			if(k!=0)
				cout<<"Pair "<<i<<": "<<k<<" segments."<<endl;
			else
				cout<<"Pair "<<i<<": impossible."<<endl;
			
		}
		cout<<endl;

	}

	return(0);
}