import java.io.BufferedReader;
import java.io.*;
import java.util.*;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Collections;
import java.util.Arrays;

public class Main {
	public static void main(final String[] args){
    
    final Scanner sc = new Scanner(System.in);
    //final List<Long> list = new ArrayList<>();

    String s = sc.next();
    int count = 0;

    for(int i = 0; i < 4 ; i++){
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    }

    if(count == 2){
        System.out.println("Yes");
    }else{
        System.out.println("No");
    }

    
    






    

    



    
  

    


    


    

    
    
    



    





}
} import java.io.BufferedReader; BufferedReader java.io import java.io.*; io.* java import java.util.*; util.* java import java.util.ArrayList; ArrayList java.util import java.util.Iterator; Iterator java.util import java.util.List; List java.util import java.util.Collections; Collections java.util import java.util.Arrays; Arrays java.util public class Main {
	public static void main(final String[] args){
    
    final Scanner sc = new Scanner(System.in);
    //final List<Long> list = new ArrayList<>();

    String s = sc.next();
    int count = 0;

    for(int i = 0; i < 4 ; i++){
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    }

    if(count == 2){
        System.out.println("Yes");
    }else{
        System.out.println("No");
    }

    
    






    

    



    
  

    


    


    

    
    
    



    





}
} Main public static void main(final String[] args){
    
    final Scanner sc = new Scanner(System.in);
    //final List<Long> list = new ArrayList<>();

    String s = sc.next();
    int count = 0;

    for(int i = 0; i < 4 ; i++){
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    }

    if(count == 2){
        System.out.println("Yes");
    }else{
        System.out.println("No");
    }

    
    






    

    



    
  

    


    


    

    
    
    



    





} main {
    
    final Scanner sc = new Scanner(System.in);
    //final List<Long> list = new ArrayList<>();

    String s = sc.next();
    int count = 0;

    for(int i = 0; i < 4 ; i++){
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    }

    if(count == 2){
        System.out.println("Yes");
    }else{
        System.out.println("No");
    }

    
    






    

    



    
  

    


    


    

    
    
    



    





} final Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String s = sc.next(); s sc.next() sc.next sc int count = 0; count 0 for(int i = 0; i < 4 ; i++){
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    } int i = 0; int i = 0; i 0 i < 4 i 4 i++ i++ i {
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    } {
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    } for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        } int j = i + 1; int j = i + 1; j i + 1 i 1 j < 4 j 4 j++ j++ j {
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        } {
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        } if(s.charAt(i) == s.charAt(j)){
                count++;
            } s.charAt(i) == s.charAt(j) s.charAt(i) s.charAt s i s.charAt(j) s.charAt s j {
                count++;
            } count++ count if(count == 2){
        System.out.println("Yes");
    }else{
        System.out.println("No");
    } count == 2 count 2 {
        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" final String[] args args public class Main {
	public static void main(final String[] args){
    
    final Scanner sc = new Scanner(System.in);
    //final List<Long> list = new ArrayList<>();

    String s = sc.next();
    int count = 0;

    for(int i = 0; i < 4 ; i++){
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    }

    if(count == 2){
        System.out.println("Yes");
    }else{
        System.out.println("No");
    }

    
    






    

    



    
  

    


    


    

    
    
    



    





}
} public class Main {
	public static void main(final String[] args){
    
    final Scanner sc = new Scanner(System.in);
    //final List<Long> list = new ArrayList<>();

    String s = sc.next();
    int count = 0;

    for(int i = 0; i < 4 ; i++){
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    }

    if(count == 2){
        System.out.println("Yes");
    }else{
        System.out.println("No");
    }

    
    






    

    



    
  

    


    


    

    
    
    



    





}
} Main
import java.io.BufferedReader;
import java.io.*;
import java.util.*;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Collections;
import java.util.Arrays;

public class Main {
	public static void main(final String[] args){
    
    final Scanner sc = new Scanner(System.in);
    //final List<Long> list = new ArrayList<>();

    String s = sc.next();
    int count = 0;

    for(int i = 0; i < 4 ; i++){
        for(int j = i + 1; j < 4 ; j++){
            if(s.charAt(i) == s.charAt(j)){
                count++;
            }
        }
    }

    if(count == 2){
        System.out.println("Yes");
    }else{
        System.out.println("No");
    }

    
    






    

    



    
  

    


    


    

    
    
    



    





}
}