Промена

import java.util.Scanner;

public class Promena {

    public static int zbir(SLL<Integer> list, int pos1, int pos2){
        SLLNode<Integer> tmp=list.getFirst();
        int brojac=0;
        int sum=0;
        while (brojac!=pos1){
           tmp=tmp.succ;
           brojac++;
        }
        while(brojac!=pos2+1){
            sum+=tmp.element;
            tmp=tmp.succ;
            brojac++;
        }
        return sum;
    }
    public static void promeni(SLL<Integer> list, int pos1, int pos2){
        int sum=zbir(list,pos1,pos2);
        SLLNode<Integer> tmp=list.getFirst();

        while(tmp!=null){
            tmp=tmp.succ;
            if(tmp==null)
                break;
            list.insertBefore(sum,tmp);
            SLLNode<Integer> kopija=tmp;
            list.delete(tmp);
            tmp=kopija.succ;
        }
        System.out.println(list);
    }
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        int n=in.nextInt();

        SLL<Integer> list=new SLL<>();
        for(int i=0;i<n;i++){
            list.insertLast(in.nextInt());
        }

        int pos1=in.nextInt();
        int pos2=in.nextInt();

        promeni(list,pos1,pos2);

    }
}