public class Main { static String reverse(String s) { if(s.length()==0) return ""; return s.charAt(s.length()-1) + reverse(s.substring(0, s.length()-1)); } static void onetoN(int i,int n) { if(i>n) return; System.out.print(i+" "); onetoN(i+1,n); } static int sum(int n) { if(n==0){ return 0; } return n+sum(n-1); } public static void main(String[] args) { System.out.println("Hello World"); String v=reverse("Hello World"); System.out.println(v); System.out.println(sum(6)); } }