void bounce()
{

	char x;

	/* state a */
a:	putchar('0');
	x = getchar();
	if (x == '0') goto a; /* transition to state a */
	if (x == '1') goto b; /* transition to state b */
	goto finis;

	/* state b */
b:	putchar('0');
	x = getchar();
	if (x == '0') goto a; /* transition to state a */
	if (x == '1') goto c; /* transition to state c */
	goto finis;

	/* state 1 */
c:	putchar('0');
	x = getchar();
	if (x == '0') goto d; /* transition to state d */
	if (x == '1') goto c; /* transition to state c */
	goto finis;

	/* state d */
d:	putchar('1');
	x = getchar();
	if (x == '0') goto a; /* transition to state a */
	if (x == '1') goto c; /* transition to state c */
	goto finis;

finis:	;

}