import java.util.stream.IntStream;
import java.util.stream.Stream;

public class DemoStreamNumerici {
    public static void main(String[] args) {
        System.out.println(IntStream.rangeClosed(1, 4).sum());
        System.out.println(IntStream.rangeClosed(1, 4).average().orElseThrow());
        System.out.println(IntStream.rangeClosed(1, 4)
                .map(numero -> numero * numero).boxed().toList());
        System.out.println(Stream.of("2", "3").mapToInt(Integer::parseInt).sum());
    }
}