static int
main(void) {
 b
 a
 a
 a
 a
 a
 a
 a
 a
 b
 a
 a
 a
 a
 a
 a
 a
 a
 a
 a
 a
 a
 a
 a
 b
 a
 a
 a
 a
 a
 a
 a
 a
 a
 a
 a
 b
}