#include <algorithm>
#include <cstdio>
#include <cstring>

using namespace std;

int R, C;
int n;

int m;
int stupac[20];
char mapa[16][16+1];
char a[256][257];

int hsh( int r, int c ) { return r*C + c; }

int dr[5] = { 0, 1, 0, -1, 0 };
int dc[5] = { 1, 0, -1, 0, 0 };

int main( void ) {
   while( scanf( "%d%d", &R, &C ) == 2 ) {
      if( R == 0 && C == 0 ) break;

      n = R*C;

      for( int r = 0; r < R; ++r ) 
         scanf( "%s", mapa[r] );

      memset( a, 0, sizeof a );
      for( int r = 0; r < R; ++r ) {
         for( int c = 0; c < C; ++c ) {
            if( mapa[r][c] == 'X' ) {
               a[hsh(r,c)][n] = 1;
            } else {
               a[hsh(r,c)][n] = 0;
            }

            for( int d = 0; d < 5; ++d ) {
               int rr = r + dr[d];
               int cc = c + dc[d];
               
               if( rr < 0 || rr >= R ) continue;
               if( cc < 0 || cc >= C ) continue;

               a[hsh(r,c)][hsh(rr,cc)] = 1;
            }
         }
      }

      int r = 0, c, i, j;
      m = 0;

      for( c = 0; c < n; ++c ) {
         
         for( i = r; i < n; ++i ) 
            if( a[i][c] == 1 )
               break;
         
         if( i == n ) {
            stupac[m++] = c;
            continue;
         }

         for( j = 0; j <= n; ++j ) 
            swap( a[i][j], a[r][j] );

         for( i = 0; i < n; ++i ) {
            if( i == r ) continue;
            if( a[i][c] == 0 ) continue;
            
            for( j = 0; j <= n; ++j ) 
               a[i][j] ^= a[r][j];
         }
         
         ++r;

      }

      int ok = 1;
      for( i = r; i < n; ++i ) 
         if( a[i][n] == 1 ) 
            ok = 0;
      
      if( !ok ) {
         printf( "Damaged billboard.\n" );
         continue;
      }

      int ret = 1000000000;

      for( int mask = 0; mask < (1<<m); ++mask ) {
         int cost = 0;
         for( int j = 0; j < m; ++j )
            if( (mask>>j)&1 )
               ++cost;
   
         for( int i = 0; i < r; ++i ) {
            int parnost = a[i][n];
            for( int j = 0; j < m; ++j )
               if( (mask>>j)&1 )
                  parnost ^= a[i][stupac[j]];

            if( parnost ) ++cost;
         }
         
         ret <?= cost;
      }
      printf( "You have to tap %d tiles.\n", ret );
   }
   return 0;
}