double  d=84.54;

d++;

int c=d/2;

int day = 3;

switch(day){

   case 1:

   case 3:

   case 5:

         System.out.print("学钢琴！");

       break;

   case 2:

         System.out.print("学英语！");

   default:

         System.out.print("去必胜客吃饭！");

}

int a = 10;

int b = 20;

int c = a + b;

int d = a - b;

System.out.println("c =" + c);

System.out.println("d =" + d);