#include <cstdio>
#include <algorithm>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <cmath>
#include <iostream>
#include <sstream>

using namespace std;

typedef vector<int> VI;
typedef vector<VI> VII;
typedef vector<string> VS;
typedef long long lint;
typedef long long LL;
typedef string ST;

#define VAR(v,n) typeof(n) v=(n)
#define REP(i,n) for(int i=0; i<(n); i++)
#define FOR(i,a,b) for(int i=(a); i<=(b); i++)
#define FORD(i,a,b) for(int i=(a); i>=(b); i--)
#define FOREACH(i,c) for(VAR(i,(c).begin()); i!=(c).end(); i++)

#define PB push_back
#define PF push_front
#define PI pair<int,int>
#define MP make_pair
#define FI first
#define SE second
#define VR vector
#define IT iterator
#define ALL(x) (x).begin(),(x).end()
#define SIZE(x) ((int)(x).size())
#define CLEAR(c,w) memset(c,w,sizeof(c))
#define M 25

int n,m;
char S[M][M];
int T[M][M],W[M][M];
int res,il;


int main() {
	scanf("%d%d",&m,&n);
		
	while (m && n) {
		REP(i,m) scanf("%s",S[i]);
		REP(i,m) REP(j,n) T[i][j]=(S[i][j]=='X');
		
		res=m*n+1;
		REP(i,(1<<n)) {
			REP(j,m) REP(k,n) W[j][k]=T[j][k];
			il=0;
			
			REP(j,n) if (i&(1<<j)) {
				if (j>0) W[0][j-1]^=1;
				W[0][j]^=1;
				if (j<n-1) W[0][j+1]^=1;
				if (m>1) W[1][j]^=1;
				il++;
			}
			
			// solve
			FOR(j,1,m-1) {
				REP(k,n) if (W[j-1][k]) {
					W[j-1][k]^=1;
					if (k>0) W[j][k-1]^=1;
					W[j][k]^=1;
					if (k<n-1) W[j][k+1]^=1;
					if (j<m-1) W[j+1][k]^=1;
					il++;
				}
			}
			
			int f=1;
			REP(j,n) if (W[m-1][j]) f=0;
			if (f) res=min(res,il);
		}
		
		if (res==m*n+1){
			printf("Damaged billboard.\n");
		} else {
			printf("You have to tap %d tiles.\n",res);
		}	
		
		scanf("%d%d",&m,&n);
	}
		
	return 0;
}