import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    String s1[] = s.split("");
    Arrays.sort(s1);
    if (!(s1[0].equals(s1[3]))){
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }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 s1[] = s.split("");
    Arrays.sort(s1);
    if (!(s1[0].equals(s1[3]))){
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    String s1[] = s.split("");
    Arrays.sort(s1);
    if (!(s1[0].equals(s1[3]))){
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  } main {
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    String s1[] = s.split("");
    Arrays.sort(s1);
    if (!(s1[0].equals(s1[3]))){
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }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 s1[] = s.split(""); s1 s.split("") s.split s "" Arrays.sort(s1) Arrays.sort Arrays s1 if (!(s1[0].equals(s1[3]))){
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    } !(s1[0].equals(s1[3])) (s1[0].equals(s1[3])) s1[0].equals s1[0] s1 0 s1[3] s1 3 {
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    } if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      } s1[0].equals(s1[1]) && s1[2].equals(s1[3]) s1[0].equals(s1[1]) s1[0].equals s1[0] s1 0 s1[1] s1 1 s1[2].equals(s1[3]) s1[2].equals s1[2] s1 2 s1[3] s1 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" {
      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 s1[] = s.split("");
    Arrays.sort(s1);
    if (!(s1[0].equals(s1[3]))){
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }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 s1[] = s.split("");
    Arrays.sort(s1);
    if (!(s1[0].equals(s1[3]))){
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }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 s1[] = s.split("");
    Arrays.sort(s1);
    if (!(s1[0].equals(s1[3]))){
      if (s1[0].equals(s1[1]) && s1[2].equals(s1[3])){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }
    }else{
      System.out.println("No");
    }
  }
}
