#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <cstring>

#define FOR(a,b,c) for(int a=b;a<=c;a++)
#define REP(a,c) for(int a=0;a<c;a++)
#define ROF(a,b,c) for(int a=b;a>=c;a--)
#define WT while(1)
#define GETI(a) scanf("%d", &a)
#define BZ(a) memset(a,0,sizeof(a))
#define FILL(a,b) fill(a,a+(sizeof(a)/sizeof(a[0])),b)
#define FOREACH(a,b) for(__typeof((b).begin()) a=(b).begin(); a!=(b).end();a++)
#define D(args...) printf(args)

using namespace std;

int r, c;

char tmpmapa[100][100];
char mapa[100][100];
int val[100][100];

const int dx[] = { 0, -1, 1, 0 , 0};
const int dy[] = { 0, 0,  0,-1, 1};

int main()
{
	while(1) {
		scanf("%d%d", &r, &c) ;
		if(r==0 && c==0) break;
		REP(i,r) REP(j, c) scanf(" %c", &tmpmapa[i][j]);
		
		if (c>r) {
		    REP(i,100) REP(j, 100)  mapa[j][i] =tmpmapa[i][j];
		    swap(c,r);
		} else {
		    REP(i,100) REP(j, 100)  mapa[i][j] =tmpmapa[i][j];		
		}
		
		int best = r*c+100;
		REP(s, (1<<c))  {

			int ile = 0;
			bool ok = true;

			REP(i, r) REP(j, c) val[i][j] = (mapa[i][j]=='X')?1:0;
			REP(i, c) if(s&(1<<i)) {
				ile++;
				if(ile >= best) goto nast;
				int j=  0;
				REP(k, 5) if(i+dx[k]>=0 && i+dx[k]<c && j+dy[k]>=0 && j+dy[k]<r) val[j+dy[k]][i+dx[k]] = 1 - val[j+dy[k]][i+dx[k]];

			}
			FOR(j, 1, r-1) REP(i, c) if(val[j-1][i] == 1) {
				ile++;
				if(ile >= best) goto nast;
												
				REP(k, 5) {				
				    int px=i+dx[k];
				    int py=j+dy[k];
				    if(px>=0 && px<c &&  py<r) val[py][px] = 1 - val[py][px];
				}
			}
			REP(i, c) if(val[r-1][i] == 1) ok = false;
			if(ok) best = min(best, ile);
			nast: ;
		}
		if(best > r*c) puts("Damaged billboard.");
		else printf("You have to tap %d tiles.\n", best);
	}
	return 0;
}