import java.util.Arrays;
import java.util.Scanner;

public class Main {

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

} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

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

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

} Main
import java.util.Arrays;
import java.util.Scanner;

public class Main {

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

}
