#include<vector>
#include<set>
#include<map>
#include<string>
#include<iostream>
#include<sstream>
#include<deque>
using namespace std;
  bool orig[18][18],mat[18][18];
void klik(int r,int c)
{
  mat[r-1][c]=!mat[r-1][c];
  mat[r+1][c]=!mat[r+1][c];
  mat[r][c-1]=!mat[r][c-1];
  mat[r][c+1]=!mat[r][c+1];
  mat[r][c]=!mat[r][c];
}
string bin(int mask)
{
string s="";
  for (int i=0;i<10;i++)
    if ((mask&(1<<i))!=0)
      s+="1";
	else 
s+="0";
return s;
}
int main()
{
  int r,c;
  while(cin>>r>>c,c+r)
  { getchar();
    for (int i=1;i<=r;i++)
    {
	for (int j=1;j<=c;j++)
	  orig[i][j]=getchar()=='X';
	getchar();
    }
    int mask=0;
    for (int i=1;i<=c;i++)
    if (orig[1][i])
	mask|=(1<<i);
    int origm=mask;
    int hran=max(5,(r*c)/2);
    int curbest=hran;
    while(1)
    {
	int curpoc=0;
    //    cout<<"         "<<bin(mask)<<endl;
        for (int i=1;i<=r;i++) 
          for (int j=1;j<=c;j++) 
             mat[i][j]=orig[i][j];
	for (int i=1;i<=c;i++)
	  if ((mask&(1<<i))!=0)
	    klik(1,i),curpoc++;  

        for (int i=2;i<=r;i++)
	  for (int j=1;j<=c;j++)
	    if (mat[i-1][j])
            {
	        if (curpoc+1>=curbest)
			goto konec;
		klik(i,j),curpoc++;
            }
//	cout<<"curpoc "<<curpoc<<endl;
 

        konec:
	bool notok=0;
	for (int i=1;i<=c;i++)
	  notok|=mat[r][i];
        if (notok==0)
	  curbest=min(curbest,curpoc);
	if (mask==0) break;
	mask--;
	mask&=origm;
    }
    if (curbest==hran)
      cout<<"Damaged billboard."<<endl;
    else
	cout<<"You have to tap "<<curbest<<" tiles."<<endl;
    
  }

}