
int main()
{
	char a[101][101];
	int n,i,j,m;
	scanf("%d",&n);	
	for (i=0;i<n;i++){
		for (j=0;j<n;j++){
			scanf("%c",&a[i][j]);
	                  if('\n'==a[i][j]){--j;}
                                    }
	                 }
	scanf("%d",&m);
         while(--m>0)
        {
	for (i=0;i<n;i++)
	 for( j = 0; j < n; j++)

            {

                if(a[i][j] == '@')

                {

                    if( i-1 >= 0 && a[i-1][j] == '.')

                        a[i-1][j] = '*';

                    if( i+1<n&&a[i+1][j] == '.')

                        a[i+1][j] = '*';

                    if( j-1 >= 0  &&a[i][j-1] == '.')

                        a[i][j-1] = '*';

                    if( j+1 < n  &&a[i][j+1] == '.')

                       a[i][j+1] = '*';

                }

            }

 

        for( i = 0; i < n; i++)

            for( j = 0; j < n; j++)

                if(a[i][j] == '*')

                    a[i][j] = '@';

             

    }

 

    int sum = 0;

    for( i = 0; i < n; i++)

        for( j = 0; j < n; j++)

                if(a[i][j] == '@')

                    ++sum;

 

    printf("%d\n",sum);

 

    return 0;

}
