import java.util.Scanner;

public class Main {

	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		String s = in.nextLine();
		char[] a = s.toCharArray();

		String ans;

		if(!(a[0] == a[1] && a[0] == a[2] && a[0] == a[3]) && ((a[0] == a[2] && a[1] == a[3]) || (a[0] == a[3] && a[1] == a[2]) || (a[0] == a[1] && a[2] == a[3])))
ans = "Yes";
else
	ans = "No";

		System.out.println(ans);
	}

}


//import java.util.Scanner;
//
//public class Main {
//
//	public static void main(String[] args){
//		Scanner in = new Scanner(System.in);
//		int n = in.nextInt();
//
//		for(int i = 0; i < n; i++)
//
//		System.out.println(ans);
//	}
//
//}
/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