import java.util.*;
public class Main{
	public static void main(String args[]) {
		Scanner sc=new Scanner(System.in);
		String S=sc.next();
		sc.close();
		int i=0;
		for(int j=0;j<3;j++) {
			for(int k=j+1;k<S.length();k++) {
				if(S.charAt(j)==S.charAt(k)) {
					i++;
				}
			}
		}
		if(i==2) {
			System.out.println("Yes");
		}else {
			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