import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        String s=sc.nextLine();
        char[] array=s.toCharArray();
        if(array[0]==array[1] && array[1]==array[2] && array[2]==array[3])
            System.out.println("No");
        else if(array[0]==array[1] && array[2]==array[3])
            System.out.println("Yes");
        else if(array[0]==array[2] && array[1]==array[3])
            System.out.println("Yes");
        else if(array[0]==array[3] && array[1]==array[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