public static boolean flag = false;

public static void tree(int limit ,int temp){

    for( int i = 2 ;i<limit-temp;i=i+2){

        for(int j=0;j<limit-i;j++){
            System.out.print(" ");
        }
        for(int k=0;k<=i;k++){
            System.out.print("* ");

        }

        System.out.println();
    }
    flag = false;
}
public static void main(String[] args) throws NumberFormatException, IOException {
    Scanner sc=new Scanner(System.in);

    System.out.println("Enter No of Days:");

int days=sc.nextInt();

    boolean first = true;

    if(days<=1){
        System.out.println("You cannot generate christmas tree");
        return;
    }

    if(days>20){
        System.out.println("Tree is no more");
        return;

    }

    int n = days+1;
    int limit = n + n;
    int temp = 0;
    for(int i=1;i<=days+1;i++){

        tree(limit,temp);
        temp+=3;
    }
    for(int i=0;i<2;i++){
        for(int j=0;j<limit;j++){
            System.out.print(" ");
        }
        System.out.println("*");
    }
}