Test.java

class Test {
  public static void main(String[] args) {
    List<Integer> voterA = Arrays.asList(1,2,3,4,5);
    List<Integer> voterB = Arrays.asList(1,2,3,4,5);
    List<List<Integer>> votes = Arrays.asList(voterA, voterB);
    
    System.out.println(
        IntStream.range(0, votes.stream().mapToInt(List::size).max().getAsInt())
           .mapToInt(i -> votes.stream().mapToInt(voter -> voter.get(i)).sum())
           .collect(Collectors.toList()));
  }
}