(defn pars [str]
	(if (boolean (re-find #"\+" str))
		(let [xp (split str #"\+" 2)]
			(+ (pars (first xp)) (pars (first (rest xp))))
		)
		(if (boolean (re-find #"\-" str))
			(let [xp (split str #"\-" 2)]
				(- (pars (first xp)) (pars (first(rest xp))))
			)
			(read-string str)
		)
	)
)