import java.util.*;

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

    Arrays.sort(c); 	    

    if(c[0]==c[1] && c[2]==c[3] && c[0]!=c[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.next();
    char[]c = S.toCharArray();

    Arrays.sort(c); 	    

    if(c[0]==c[1] && c[2]==c[3] && c[0]!=c[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.next();
    char[]c = S.toCharArray();

    Arrays.sort(c); 	    

    if(c[0]==c[1] && c[2]==c[3] && c[0]!=c[3]){
 	System.out.println("Yes");
    }else{
    System.out.println("No");    
      }
    } main {
    
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    char[]c = S.toCharArray();

    Arrays.sort(c); 	    

    if(c[0]==c[1] && c[2]==c[3] && c[0]!=c[3]){
 	System.out.println("Yes");
    }else{
    System.out.println("No");    
      }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String S = sc.next(); S sc.next() sc.next sc char[]c = S.toCharArray(); c S.toCharArray() S.toCharArray S Arrays.sort(c) Arrays.sort Arrays c if(c[0]==c[1] && c[2]==c[3] && c[0]!=c[3]){
 	System.out.println("Yes");
    }else{
    System.out.println("No");    
      } c[0]==c[1] && c[2]==c[3] && c[0]!=c[3] c[0]==c[1] && c[2]==c[3] && c[0]!=c[3] c[0]==c[1] c[0] c 0 c[1] c 1 c[2]==c[3] c[2] c 2 c[3] c 3 c[0]!=c[3] c[0] c 0 c[3] c 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.next();
    char[]c = S.toCharArray();

    Arrays.sort(c); 	    

    if(c[0]==c[1] && c[2]==c[3] && c[0]!=c[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.next();
    char[]c = S.toCharArray();

    Arrays.sort(c); 	    

    if(c[0]==c[1] && c[2]==c[3] && c[0]!=c[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.next();
    char[]c = S.toCharArray();

    Arrays.sort(c); 	    

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