Gaus Trick

package com.company;


import java.util.*;
import java.util.stream.Collectors;

public class Main {



    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        List<Integer> numbers = Arrays.stream(sc.nextLine().split(" "))
                .map(Integer::parseInt)
                .collect(Collectors.toList());

        List<Integer>modified = new ArrayList<>();

        for (int i = 0; i < numbers.size() / 2; i++) {
            int lastIndex = numbers.size() - 1;
            int sum = numbers.get(i) + numbers.get(lastIndex - i);
            modified.add(sum);

            if (numbers.size() %2 != 0 ){
                int middleIndex = numbers.size() / 2;
                modified.add( numbers.get(middleIndex));
            }

        }
        numbers = modified;

        for (int number : numbers) {
            System.out.print(number + " ");
        }

    }
}