(set-info :smt-lib-version 2.5) (set-logic QF_S) (set-info :status sat) (set-option :strings-exp true) (declare-fun x () String) (assert (str.in.re x (re.* (re.++ (re.* (str.to.re "a") ) (str.to.re "b") )) )) (assert (= (str.len x) 3)) (check-sat)