int main(){
char a[101][101],q;
int k,n,i,j,m,s;
scanf("%d",&n);
scanf("%c",&q);
for (i=1;i<=n;i++)
for (j=1;j<=n;j++){
	scanf("%c",&a[i][j]);
if (j==n) scanf("%c",&q);
}
scanf("%d",&m);
for (k=2;k<=m;k++){
for (i=1;i<=n;i++)
for (j=1;j<=n;j++)
if (a[i][j]=='@'){
	if ((i-1!=0)&&(a[i-1][j]=='.')) a[i-1][j]=',';
	if ((i+1!=n+1)&&(a[i+1][j]=='.')) a[i+1][j]=',';
	if ((j-1!=0)&&(a[i][j-1]=='.')) a[i][j-1]=',';
	if ((j+1!=0)&&(a[i][j+1]=='.')) a[i][j+1]=',';
}
for (i=1;i<=n;i++)
for (j=1;j<=n;j++)
if (a[i][j]==',') a[i][j]='@';
}
s=0;
for (i=1;i<=n;i++)
for (j=1;j<=n;j++)
if (a[i][j]=='@') s=s+1;
printf("%d",s);
return 0;
}