import java.util.*;
class triangle {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("please input an integer:");
int row = sc.nextInt();
for(int i = 1; i <= row; i++) {
for(int j = 1; j <= row - i; j++) {
//1.输入前面的空格
System.out.print(" ");
}
//2.输入*和空格
for(int k = 1; k <= 2*i - 1; k++) {
//3.第一行与最后一行全部打印*
if (i == 1 || i ==row) {
System.out.print("*");
}else {
if(k == 1 || k == 2*i -1) {
System.out.print("*");
}else {
System.out.print(" ");
}
}
}
//换行
System.out.println();
}
}
}