import java.util.*;
public class Main{
  public static void main(String[]args){
      Scanner sc = new Scanner(System.in);

      String S =sc.nextLine();

      char c;
      char[] data  = new char[S.length()];
      int count  = 0;

      for(int i = 0;i<S.length();i++){
        c = S.charAt(i);
        data[i] = c;
      }
      for(int i =0;i<4;i++){
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      }
      if(count==2){
        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.nextLine();

      char c;
      char[] data  = new char[S.length()];
      int count  = 0;

      for(int i = 0;i<S.length();i++){
        c = S.charAt(i);
        data[i] = c;
      }
      for(int i =0;i<4;i++){
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      }
      if(count==2){
        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.nextLine();

      char c;
      char[] data  = new char[S.length()];
      int count  = 0;

      for(int i = 0;i<S.length();i++){
        c = S.charAt(i);
        data[i] = c;
      }
      for(int i =0;i<4;i++){
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      }
      if(count==2){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }


  } main {
      Scanner sc = new Scanner(System.in);

      String S =sc.nextLine();

      char c;
      char[] data  = new char[S.length()];
      int count  = 0;

      for(int i = 0;i<S.length();i++){
        c = S.charAt(i);
        data[i] = c;
      }
      for(int i =0;i<4;i++){
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      }
      if(count==2){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }


  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String S =sc.nextLine(); S sc.nextLine() sc.nextLine sc char c; c char[] data  = new char[S.length()]; data new char[S.length()] S.length() S.length S int count  = 0; count 0 for(int i = 0;i<S.length();i++){
        c = S.charAt(i);
        data[i] = c;
      } int i = 0; int i = 0; i 0 i<S.length() i S.length() S.length S i++ i++ i {
        c = S.charAt(i);
        data[i] = c;
      } {
        c = S.charAt(i);
        data[i] = c;
      } c = S.charAt(i) c S.charAt(i) S.charAt S i data[i] = c data[i] data i c for(int i =0;i<4;i++){
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      } int i =0; int i =0; i 0 i<4 i 4 i++ i++ i {
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      } {
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      } for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        } int j = i+1; int j = i+1; j i+1 i 1 j<4 j 4 j++ j++ j {
          if(data[i]==data[j]){
            count++;
          }
        } {
          if(data[i]==data[j]){
            count++;
          }
        } if(data[i]==data[j]){
            count++;
          } data[i]==data[j] data[i] data i data[j] data j {
            count++;
          } count++ count if(count==2){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      } count==2 count 2 {
        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.nextLine();

      char c;
      char[] data  = new char[S.length()];
      int count  = 0;

      for(int i = 0;i<S.length();i++){
        c = S.charAt(i);
        data[i] = c;
      }
      for(int i =0;i<4;i++){
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      }
      if(count==2){
        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.nextLine();

      char c;
      char[] data  = new char[S.length()];
      int count  = 0;

      for(int i = 0;i<S.length();i++){
        c = S.charAt(i);
        data[i] = c;
      }
      for(int i =0;i<4;i++){
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      }
      if(count==2){
        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.nextLine();

      char c;
      char[] data  = new char[S.length()];
      int count  = 0;

      for(int i = 0;i<S.length();i++){
        c = S.charAt(i);
        data[i] = c;
      }
      for(int i =0;i<4;i++){
        for(int j = i+1;j<4;j++){
          if(data[i]==data[j]){
            count++;
          }
        }
      }
      if(count==2){
        System.out.println("Yes");
      }else{
        System.out.println("No");
      }


  }
}