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