Cikli

import java.util.Scanner;

public class suns {

    public static void main (String [] args) {
        Scanner scanner = new Scanner(System.in);

        int n = Integer.parseInt(scanner.nextLine());

        int stars = 0;
        if(n % 2 == 0) {
            stars = 2;
        }else{
            stars = 1;
        }
        for (int i = 0; i  < Math.ceil(n / 2.0) ; i++) {
            String row =
                    repeatStr("_",(n - stars) / 2 )
                      + repeatStr("*",stars)
                     +repeatStr("_",(n - stars) / 2);

            stars += 2;
            System.out.println(row);
        }
        for (int i = 0; i < n / 2; i++) {
             String row = "|" + repeatStr("*",n-2) + "|";
            System.out.println(row);
        }

    }

static String repeatStr(String strToRepeat, int count ) {
        String text = "";
    for (int i = 0; i < count ; i++) {
        text = text + strToRepeat;
    }
    return strToRepeat;
}
}