import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        String str = sc.next();

        if(str.charAt(0)==str.charAt(1) && str.charAt(2)==str.charAt(3) && str.charAt(1)!=str.charAt(2)){
            System.out.println("Yes");
        }
        else if(str.charAt(0)==str.charAt(2) && str.charAt(1)==str.charAt(3) && str.charAt(2)!=str.charAt(1)){
            System.out.println("Yes");
        }
        else if(str.charAt(0)==str.charAt(3) && str.charAt(1)==str.charAt(2) && str.charAt(3)!=str.charAt(1)){
            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