//***************************************************************************
//???????
//??? ??n???????? 
//?????? 
//*************************************************************************** 
void search(int l); 
int n, m, p[101][101] = {0}, c = 0;
char a[101][101];
int main()                                     //??? 
{
    cin>>n;                                
    for(int i = 0; i < n; i++)                 //???? 
            for(int j = 0; j < n; j++)
                    cin>>a[i][j];
     cin>>m;
     search(1);                               //???? 
     for(int i = 0; i < n; i++)               //???????? 
            for(int j = 0; j < n; j++)
                    if(a[i][j] == '@')
                               c++;
     cout<<c<<endl; 
     return 0; 
}
void search(int l)                           //???????l???????? 
{ 
      for(int i = 0; i < n; i++)
                      for(int j = 0; j < n; j++)
                      {
                              if(a[i][j] == '@')  //??????????????????? 
                              {
                                         if(i > 0 && a[i - 1][j] == '.')
                                              p[i - 1][j] = 1;
                                         if(i < n - 1 && a[i + 1][j] == '.')
                                              p[i + 1][j] = 1;
                                         if(j > 0 && a[i][j - 1] == '.')
                                              p[i][j - 1] = 1;
                                         if(j < n - 1 && a[i][j + 1] == '.')
                                              p[i][j + 1] = 1;
                              }
                      } 
      for(int k = 0; k < n; k++)                 //???????@ 
                     for(int h = 0; h < n; h++)
                             if(p[k][h] == 1)
                                        a[k][h] = '@';
      if(l < m - 1)                              //????????????? 
           search(l + 1); 
} 
