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