import java.util.*;
import java.util.Scanner;


public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        String a = sc.next();
        char b[] = new char[4];
        b[0] = a.charAt(0);
        b[1] = a.charAt(1);
        b[2] = a.charAt(2);
        b[3] = a.charAt(3);
        
        Arrays.sort(b);
        
        if(b[0]==b[1] && b[1]!=b[2] && b[2] == b[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
} import java.util.*; util.* java import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        String a = sc.next();
        char b[] = new char[4];
        b[0] = a.charAt(0);
        b[1] = a.charAt(1);
        b[2] = a.charAt(2);
        b[3] = a.charAt(3);
        
        Arrays.sort(b);
        
        if(b[0]==b[1] && b[1]!=b[2] && b[2] == b[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        String a = sc.next();
        char b[] = new char[4];
        b[0] = a.charAt(0);
        b[1] = a.charAt(1);
        b[2] = a.charAt(2);
        b[3] = a.charAt(3);
        
        Arrays.sort(b);
        
        if(b[0]==b[1] && b[1]!=b[2] && b[2] == b[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    } main {
        Scanner sc = new Scanner(System.in);
        
        String a = sc.next();
        char b[] = new char[4];
        b[0] = a.charAt(0);
        b[1] = a.charAt(1);
        b[2] = a.charAt(2);
        b[3] = a.charAt(3);
        
        Arrays.sort(b);
        
        if(b[0]==b[1] && b[1]!=b[2] && b[2] == b[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String a = sc.next(); a sc.next() sc.next sc char b[] = new char[4]; b new char[4] 4 b[0] = a.charAt(0) b[0] b 0 a.charAt(0) a.charAt a 0 b[1] = a.charAt(1) b[1] b 1 a.charAt(1) a.charAt a 1 b[2] = a.charAt(2) b[2] b 2 a.charAt(2) a.charAt a 2 b[3] = a.charAt(3) b[3] b 3 a.charAt(3) a.charAt a 3 Arrays.sort(b) Arrays.sort Arrays b if(b[0]==b[1] && b[1]!=b[2] && b[2] == b[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        } b[0]==b[1] && b[1]!=b[2] && b[2] == b[3] b[0]==b[1] && b[1]!=b[2] && b[2] == b[3] b[0]==b[1] b[0] b 0 b[1] b 1 b[1]!=b[2] b[1] b 1 b[2] b 2 b[2] == b[3] b[2] b 2 b[3] b 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) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        String a = sc.next();
        char b[] = new char[4];
        b[0] = a.charAt(0);
        b[1] = a.charAt(1);
        b[2] = a.charAt(2);
        b[3] = a.charAt(3);
        
        Arrays.sort(b);
        
        if(b[0]==b[1] && b[1]!=b[2] && b[2] == b[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        String a = sc.next();
        char b[] = new char[4];
        b[0] = a.charAt(0);
        b[1] = a.charAt(1);
        b[2] = a.charAt(2);
        b[3] = a.charAt(3);
        
        Arrays.sort(b);
        
        if(b[0]==b[1] && b[1]!=b[2] && b[2] == b[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
} Main
import java.util.*;
import java.util.Scanner;


public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        String a = sc.next();
        char b[] = new char[4];
        b[0] = a.charAt(0);
        b[1] = a.charAt(1);
        b[2] = a.charAt(2);
        b[3] = a.charAt(3);
        
        Arrays.sort(b);
        
        if(b[0]==b[1] && b[1]!=b[2] && b[2] == b[3]){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
}
