#include <cstdio>

using namespace std;

int R, C;
char wej2[16][16];
int ilosc;

inline void change(int i, int j)
{
	wej2[i][j] = !wej2[i][j];
	if (i > 0)
		wej2[i - 1][j] = !wej2[i - 1][j];
	if (j > 0)
		wej2[i][j - 1] = !wej2[i][j - 1];
	if (i < R - 1)
		wej2[i + 1][j] = !wej2[i + 1][j];
	if (j < C - 1)
		wej2[i][j + 1] = !wej2[i][j + 1];

	++ilosc;
}

int main()
{
	char wej[16][16];
	int i, j, k;
	bool ok;
	int min_ilosc;

	scanf("%d%d", &R, &C);

	while ((R != 0) && (C != 0))
	{
		getchar();
		for (i = 0; i < R; ++i)
		{
			for (j = 0; j < C; ++j)
				wej[i][j] = getchar() == 'X' ? 1 : 0;

			getchar();
		}

		min_ilosc = 1000;

		for (i = 0; i < (1 << C); ++i)
		{
			for (j = 0; j < R; ++j)
				for (k = 0; k < C; ++k)
					wej2[j][k] = wej[j][k];

			ilosc = 0;
			for (j = 0; j < C; ++j)
				if (i & (1 << j))
					change(0, j);

			for (j = 1; j < R; ++j)
				for (k = 0; k < C; ++k)
					if (wej2[j - 1][k])
						change(j, k);
				
			ok = true;
			for (k = 0; k < C; ++k)
				if (wej2[R - 1][k])
					ok = false;

			if (ok)
				if (ilosc < min_ilosc)
					min_ilosc = ilosc;
		}

		if (min_ilosc < 1000)
			printf("You have to tap %d tiles.\n", min_ilosc);
		else
			printf("Damaged billboard.\n");
		scanf("%d%d", &R, &C);
	}

	return 0;

}