import java.util.Scanner;
class Main
{
	public static void main(String args[])
	{
		Scanner sc=new Scanner(System.in);
        String s=sc.next();
        int sum=0;
        for(int i=0; i<4; i++){
            for(int j=0; j<4; j++){
                if(s.charAt(i)==s.charAt(j)){
                    sum++;
                }
            }
        }
        if(sum==8){
            System.out.println("Yes");
        }
        else{
            System.out.println("No");
        }
        sc.close();
    }
}
/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