func main()
	var s: []char :: cui@input()
	var n: int :: ^s
	
	var dic: dict<[]char, bool> :: #dict<[]char, bool>
	for id(0, 2 ^ (n - 1) - 1)
		var ns: []char :: #[n]char
		var ii: int :: id
		var mn: int :: 0
		var mx: int :: n - 1
		for i(0, n - 1)
			if(ii % 2 = 0)
				do ns[i] :: s[mn]
				do mn :+ 1
			else
				do ns[i] :: s[mx]
				do mx :- 1
			end if
			do ii :/ 2
		end for
		do dic.add(ns, true)
	end for
	var ans: int :: ^dic
	do cui@print("\{ans}\n")
end func