int main()
{
  int count=0,t,n,i,j,m;
  char a[1000][1000],b[1000][1000];
  scanf("%d\n",&n);
  for (i=0;i<n;i++)
  {
   for (j=0;j<n;j++)
    {
        if (j==n-1)
        scanf("%c\n",&a[i][j]);
        else
        scanf("%c",&a[i][j]);
    }
  }
  scanf("%d",&m);
  for ( t=1;t<m;t++)
  {
   for (i=0;i<n;i++)
   {
    for (j=0;j<n;j++)
    {
     if (a[i][j]=='@')
      {
      if ( (i+1)<n && a[i+1][j]=='.' )
      b[i+1][j]='@';
      
      if ( (i-1)>=0 && a[i-1][j]=='.')
      b[i-1][j]='@';
        
      if ((j+1)<n  &&  a[i][j+1]=='.')
      b[i][j+1]='@';
       
      if ((j-1)>=0  &&  a[i][j-1]=='.')
      b[i][j-1]='@';
     }
    }
   }     for (i=0;i<n;i++)
        {
            for (j=0;j<n;j++)
               {
                if (b[i][j]=='@'&&a[i][j]!='#')
                     a[i][j]='@';
               } 
        }
   }
        for (i=0;i<n;i++)
         {
            for (j=0;j<n;j++)
             {
              if (a[i][j]=='@')
                 count++;
             }
         }
    /*  for (i=0;i<n;i++)
      {
          for (j=0;j<n;j++)
            {
               if (j==n-1)
                printf("%c\n",a[i][j]);
               else 
                printf("%c",a[i][j]);
            }
      }*/
printf("%d",count);
}

