func main()
	var n: int :: cui@inputInt()
	var ans: int :: 1
	for(1, n)
		var p: int :: cui@inputInt()
		do ans :: f(ans * p)
		func f(x: int): int
			var res: int :: 0
			while(x > 0)
				do res :+ x % 10
				do x :/ 10
			end while
			if(res > 9)
				ret f(res)
			else
				ret res
			end if
		end func
	end for
	do cui@print("\{ans}\n")
end func