import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        char array[] = s.toCharArray();
        Arrays.sort(array);

        if(array[0]==array[1] && array[1]!=array[2] && array[2]==array[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }

    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        char array[] = s.toCharArray();
        Arrays.sort(array);

        if(array[0]==array[1] && array[1]!=array[2] && array[2]==array[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }

    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        char array[] = s.toCharArray();
        Arrays.sort(array);

        if(array[0]==array[1] && array[1]!=array[2] && array[2]==array[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }

    } main {
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        char array[] = s.toCharArray();
        Arrays.sort(array);

        if(array[0]==array[1] && array[1]!=array[2] && array[2]==array[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }

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

        if(array[0]==array[1] && array[1]!=array[2] && array[2]==array[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }

    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        char array[] = s.toCharArray();
        Arrays.sort(array);

        if(array[0]==array[1] && array[1]!=array[2] && array[2]==array[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }

    }
} Main
import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        char array[] = s.toCharArray();
        Arrays.sort(array);

        if(array[0]==array[1] && array[1]!=array[2] && array[2]==array[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }

    }
}