class Aufgabe {
  public static void main(String[] args) {
    final int START = 1;
    final int ENDE = 20;

    int summe = 0;
    int n = 0;

    System.out.println("Lösung mit for-Schleife:");

    for(n = START; n <= ENDE; n++) {
      summe += n;
      System.out.println(summe);
    }

    System.out.println("Lösung mit while-Schleife:");

    summe = 0;
    n = START;

    while(n <= 20) {
      summe += n;
      System.out.println(summe);
      n++;
    }

    System.out.println("Lösung mit do-while-Schleife:");

    summe = 0;
    n = START;

    do {
      summe += n;
      System.out.println(summe);
      n++;
    } while (n <= ENDE);
  }
}