import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		char [] sArray = s.toCharArray();
		int count = 0;
		for (int i = 1; i < 4; i++) {
			if (sArray[0] == sArray[i]) {
				count++;
				sArray[i] = 0;
			}
		}
		if (count != 1) {
			System.out.println("No");
			return;
		} else {
			for (int i = 1; i < 4; i++) {
				if (sArray[i] == 0) {
					continue;
				} else {
					for (int j = i + 1; j < 4; j++) {
						if (sArray[i] == sArray[j]) {
							System.out.println("Yes");
							return;
						}
					}
				}
			}
		}
		System.out.println("No");
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz