Structure within Union

#include<stdio.h>

#include<conio.h>

union X

{

  int a,b;

  struct Y

  {

   int c,d;

  }y;

}x;

void main()

{

 clrscr();

  x.a=10,x.b=20,x.y.c=30,x.y.d=40;

  printf("First Number=%d\n",x.a);

  printf("Second Number=%d\n",x.b);

  printf("Third Number=%d\n",x.y.c);

  printf("Fourth Number=%d",x.y.d);

 getch();

}