Scanner myInput = new Scanner (System.in);
int a;
int b;
int soucet;
int prumer;
System.out.print("Zadej prvni cislo");
a = myInput.nextInt();
System.out.print("Zadej druhe cislo");
b = myInput.nextInt();
soucet = a + b;
prumer = (a+b)/2;
System.out.printf("Sum=%d\n", soucet);
System.out.print(prumer);

Nevim jak tam zakombinovat cyklus na nekonecne zadavani cisel dokud se nezada nula a nasledne pocitani