#include <cstdio>
#include <map>
#include <string>
#include <algorithm>
using namespace std;

#define FUP(i,a,b) for(int (i)=(a); (i)<=(b); (i)++)
#define FORD(i,a,b) for(int (i)=(a); (i)>=(b); (i)--)
#define mp make_pair

int w[20][20], v[20][20];
int r,c;
int dp[20][20][1<<16];
int my;
int dx[] = { 1, 0, -1, 0 };
int dy[] = { 0, 1, 0, -1 };

inline void sw (int i, int j) {
	v[i][j] = (v[i][j]) ? 0 : 1;
	for (int d = 0; d < 4; d++) {
		int nr = i + dx[d], nc = j + dy[d];
		if (nr < 0 || nc < 0 || nr >= r || nc >= c) continue;
		v[nr][nc] = (v[nr][nc]) ? 0 : 1;
	}
}

int main(){
	while(1){
		scanf("%d%d",&r,&c);
		if (r==0&&c==0) break;
		for (int i = 0; i < r; i++) for (int j = 0; j < c; j++) {
			char c = 0;
			while ((c=getchar()) != 'X' && c != '.');
			w[i][j] = (c == 'X');
		}
		int res = 1000000000;
		for (int mask = 0; mask < (1<<c); mask++) {
			memcpy(v,w,sizeof(v));
			int cur = 0;
			for (int j = 0; j < c; j++) {
				if ((1<<j) & mask) {
					sw(0,j);
					cur++;
				}
			}
			
			for (int i = 1; i < r; i++) {
				for (int j = 0; j < c; j++) {
					if (v[i-1][j]) {
						sw(i,j);
						cur++;
					}
				}
			}
			for (int j = 0; j < c; j++) {
				if (v[r-1][j]) {
					cur = -1;
					break;
				}
			}
			if (cur >= 0) res <?= cur;
		}
		if (res < 1000000000) printf("You have to tap %d tiles.\n",res); else printf("Damaged billboard.\n");
	}

		
	return 0;
}