public class HW_10 {
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		Set<Character> hs=new HashSet<Character>();
		String target=scanner.next();
		char[] arrs=new char[target.length()];
		for (int i = 0; i < target.length(); i++) {
			hs.add(target.charAt(i));//取字符串添加到hashset中去
			arrs[i]=target.charAt(i);//将字符串抓换为数组
		}
		System.out.println(hs.size());
		System.out.println(arrs);
	}
}

用字符串.charAt()方法