#include <cstdio>

bool tab[20][20];
bool tmp[20][20];
int i,j,k,l,m,n,R,C;
char znak;
int ilosc,maks;


int sprawdz(){
	int ile=0;
	int i,j;
	
	for (i=2;i<=R;i++){
		for (j=1;j<=C;j++){
			if (tmp[i-1][j]){
				ilosc++;
				tmp[i-1][j]=!tmp[i-1][j];
				tmp[i][j-1]=!tmp[i][j-1];
				tmp[i][j]=!tmp[i][j];
				tmp[i][j+1]=!tmp[i][j+1];
				tmp[i+1][j]=!tmp[i+1][j];
			}
		}
	}
	
	bool prawda=true;
	
	for (i=1;i<=R;i++){
		for (j=1;j<=C;j++){
			if (tmp[i][j]) prawda=false;
		}
	}
	
	if (!prawda) return 1000000;
	else return ile;
	
}

int main(){
	while (1){
		scanf("%d %d\n",&R,&C);
		maks=1000000;
		
		if (R==0 && C==0) return 0;
		
		for (i=1;i<=R;i++){
			for (j=1;j<=C;j++){
				scanf("%c",&znak);	
				if (znak=='X') tab[i][j]=true;
				else tab[i][j]=false;
			}
			scanf("\n");
		}
		
		for (i=0;i<(1<<C);i++){
			ilosc=0;
			
			for (j=1;j<=R;j++)
				for (k=1;k<=C;k++)
					tmp[j][k]=tab[j][k];
			
			for (j=0;j<C;j++){
				if ((1<<j) & i){
					tmp[1][j]=!tmp[1][j];
					tmp[1][j+1]=!tmp[1][j+1];
					tmp[1][j+2]=!tmp[1][j+2];
					tmp[2][j+1]=!tmp[2][j+1];
					ilosc++;
				}
			}
			
			//bool prawda=true;
			//for (j=1;j<=C;j++) if (tab[1][j]==true) prawda=false;
			//if (!prawda) continue;
			
			ilosc+=sprawdz();
			//printf("%d\n",i);
			if (ilosc<maks) maks=ilosc;
		}
		
		if (maks>=1000000) printf("Damaged billboard.\n");
		else printf("You have to tap %d tiles.\n",maks);
	}
	
	return 0;
}