import java.util.*;
public class Main{
  public static void main(String[] args) {
    Scanner sc=new Scanner(System.in);
    String s=sc.next();
    int count=0;
    int n=0;
    for(int i=1;i<4;i++){
      if(s.charAt(0)==s.charAt(i)){
        count=count+1;
        n=i;
      }
    }
    if(n==1){
      if(s.charAt(2)==s.charAt(3)){
        count=count+1;
      }
    }
    if(n==2){
      if(s.charAt(1)==s.charAt(3)){
        count=count+1;
      }
    }
    if(n==3){
      if(s.charAt(1)==s.charAt(2)){
        count=count+1;
      }
    }
    if(count==2){
      System.out.println("Yes");
    }else{
      System.out.println("No");
    }
  }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz