(set-logic ALL)
(set-option :strings-exp true)
(set-info :status sat)
(declare-fun s () String)
(assert (str.contains s "Hello and goodbye!"))
(declare-fun x () Int)
(assert (<= (str.len s) x))
(assert (not (= (str.indexof s "goodbye" (- x 30)) (- 1))))
(check-sat)