Envío 6880

Código

class Main {
	public static void main(String[] args) {
		
		java.util.Scanner inp = new java.util.Scanner(System.in);
		String word = inp.next();
		boolean letters[] = new boolean[26];
		
		for(int i = 0; i < word.length(); i++) {
			int x = word.charAt(i) - 'a';
			
			if (letters[x]) {
				System.out.println("yes");
				return;
			} else {
				letters[x] = true;
			}
		}
		System.out.println("no");
		
		inp.close();
	}
}