 import java.util.*;
 public class Main{
	 public static void main(String arg[]){
		 Scanner sc=new Scanner(System.in);
		 String s=sc.next();
		 char ch[]=s.toCharArray();
		 Arrays.sort(ch);
		 if((ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]))
			 System.out.println("Yes");
		 else System.out.println("No");
	 }
 } import java.util.*; util.* java public class Main{
	 public static void main(String arg[]){
		 Scanner sc=new Scanner(System.in);
		 String s=sc.next();
		 char ch[]=s.toCharArray();
		 Arrays.sort(ch);
		 if((ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]))
			 System.out.println("Yes");
		 else System.out.println("No");
	 }
 } Main public static void main(String arg[]){
		 Scanner sc=new Scanner(System.in);
		 String s=sc.next();
		 char ch[]=s.toCharArray();
		 Arrays.sort(ch);
		 if((ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]))
			 System.out.println("Yes");
		 else System.out.println("No");
	 } main {
		 Scanner sc=new Scanner(System.in);
		 String s=sc.next();
		 char ch[]=s.toCharArray();
		 Arrays.sort(ch);
		 if((ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]))
			 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 ch[]=s.toCharArray(); ch s.toCharArray() s.toCharArray s Arrays.sort(ch) Arrays.sort Arrays ch if((ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]))
			 System.out.println("Yes");
		 else System.out.println("No"); (ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]) (ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]) (ch[0]==ch[1]) ch[0] ch 0 ch[1] ch 1 (ch[2]==ch[3]) ch[2] ch 2 ch[3] ch 3 (ch[0]!=ch[2]) ch[0] ch 0 ch[2] ch 2 System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" String arg[] arg public class Main{
	 public static void main(String arg[]){
		 Scanner sc=new Scanner(System.in);
		 String s=sc.next();
		 char ch[]=s.toCharArray();
		 Arrays.sort(ch);
		 if((ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]))
			 System.out.println("Yes");
		 else System.out.println("No");
	 }
 } public class Main{
	 public static void main(String arg[]){
		 Scanner sc=new Scanner(System.in);
		 String s=sc.next();
		 char ch[]=s.toCharArray();
		 Arrays.sort(ch);
		 if((ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]))
			 System.out.println("Yes");
		 else System.out.println("No");
	 }
 } Main
 import java.util.*;
 public class Main{
	 public static void main(String arg[]){
		 Scanner sc=new Scanner(System.in);
		 String s=sc.next();
		 char ch[]=s.toCharArray();
		 Arrays.sort(ch);
		 if((ch[0]==ch[1])&&(ch[2]==ch[3])&&(ch[0]!=ch[2]))
			 System.out.println("Yes");
		 else System.out.println("No");
	 }
 }