/*
 First, a string containing only letters 'A' is generated.
 Then we check its last letter is not 'B'.
 The string generation algorithm processes the string from the beginning.
*/

/***********************************************/
/*           the input program                 */
/***********************************************/
$ENTRY Go {
	e.x = <Check <F e.x>>;
}

F {
	 = ;
	t.x e.y = 'A' <F e.y>;
}

Check {
	e.X 'B' = 'F';
	e.Z = 'T';
}

/***********************************************/
/*          the residual program               */
/***********************************************/

/*
$ENTRY Go {
 e.x1 =  <Check_0 () (e.x1)>;
}


Check_0 {
 (e.x1) () =  'T';
 (e.x1) (t.y1 e.x2) =  <Check_0 (e.x1 'A') (e.x2)>;
}
*/