/* Name      : ???? 
 * Version   : 2.0
 * Date      : 2012-11-24
 * New       : ???????? 
 * Func&Feat : 
 * State     : Work
 */
char room[100][101]={0};                         //????????room[][]???????? 
void infection(int,int);
int main()
{
    int n,m,infector=0;                          //???infector??????? 
    cin>>n;
    for(int i=0;i<n;i++)cin>>room[i];
    cin>>m;
    infection(m,n);
    for(int i=0;i<n;i++)
        for(int j=0;j<n;j++)
            if(room[i][j]=='@')infector++;       //?????'@'??? 
    cout<<infector;
    return 0;
}
void infection(int day,int n)
{
    if(day>2)infection(day-1,n);
    for(int i=0;i<n;i++)
        for(int j=0;j<n;j++)
            if(room[i][j]=='.')
                if(room[i][j-1]=='@'||room[i][j+1]=='@'||room[i-1][j]=='@'||room[i+1][j]=='@')room[i][j]='$';
                                                 //???????????????????'$'?? 
    for(int i=0;i<n;i++)
        for(int j=0;j<n;j++)
            if(room[i][j]=='$')room[i][j]='@';   //????????'@'??????????? 
/*    cout<<"?"<<day<<"??"<<endl;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)cout<<room[i][j];
        cout<<endl;
    }//*/
}
