public class Solustion {
	public static boolean IsUnique(String s) {
		if (s == null) {
			return true;
		}
		if (s.length() > 256) {
			return false;
		}

		boolean[] asciiExist = new boolean[256];
		for (int i = 0; i < s.length(); i++) {
			int index = s.charAt(i);
			System.out.println(index+"!!!");
			if (asciiExist[index]) {
				return false;
			}
			asciiExist[index] = true;
		}
		return true;

	}
	public static void main(String[] args){

		System.out.print(Solution.IsUnique("2irdf329r52ql"));

	}
}