import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        String s = scan.nextLine();
        if((s.charAt(0)==s.charAt(1)&&s.charAt(2)==s.charAt(3)&&s.charAt(0)!=s.charAt(3))||(s.charAt(0)==s.charAt(2)&&s.charAt(1)==s.charAt(3)&&s.charAt(2)!=s.charAt(3))||(s.charAt(0)==s.charAt(3)&&s.charAt(1)==s.charAt(2)&&s.charAt(2)!=s.charAt(3))){
            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