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

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

		String s = sc.next();

		char[] list = s.toCharArray();

		Arrays.sort(list);

		if (list[0] == list[1] && list[2] == list[3] && list[0] != list[2]) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}
} 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);

		String s = sc.next();

		char[] list = s.toCharArray();

		Arrays.sort(list);

		if (list[0] == list[1] && list[2] == list[3] && list[0] != list[2]) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		String s = sc.next();

		char[] list = s.toCharArray();

		Arrays.sort(list);

		if (list[0] == list[1] && list[2] == list[3] && list[0] != list[2]) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

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

		String s = sc.next();

		char[] list = s.toCharArray();

		Arrays.sort(list);

		if (list[0] == list[1] && list[2] == list[3] && list[0] != list[2]) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

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

		String s = sc.next();

		char[] list = s.toCharArray();

		Arrays.sort(list);

		if (list[0] == list[1] && list[2] == list[3] && list[0] != list[2]) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		String s = sc.next();

		char[] list = s.toCharArray();

		Arrays.sort(list);

		if (list[0] == list[1] && list[2] == list[3] && list[0] != list[2]) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}
} Main
import java.util.Arrays;
import java.util.Scanner;

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

		String s = sc.next();

		char[] list = s.toCharArray();

		Arrays.sort(list);

		if (list[0] == list[1] && list[2] == list[3] && list[0] != list[2]) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

		sc.close();
	}
}