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();
		sc.close();
		Arrays.sort(S);
		if(S[0] == S[3]) System.out.println("No");
		else if(S[0] == S[1] && S[2] == S[3]) 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();
		sc.close();
		Arrays.sort(S);
		if(S[0] == S[3]) System.out.println("No");
		else if(S[0] == S[1] && S[2] == S[3]) 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();
		sc.close();
		Arrays.sort(S);
		if(S[0] == S[3]) System.out.println("No");
		else if(S[0] == S[1] && S[2] == S[3]) System.out.println("Yes");
		else System.out.println("No");
	} main {
		Scanner sc = new Scanner(System.in);
		char[] S = sc.next().toCharArray();
		sc.close();
		Arrays.sort(S);
		if(S[0] == S[3]) System.out.println("No");
		else if(S[0] == S[1] && S[2] == S[3]) 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 sc.close() sc.close sc Arrays.sort(S) Arrays.sort Arrays S if(S[0] == S[3]) System.out.println("No");
		else if(S[0] == S[1] && S[2] == S[3]) System.out.println("Yes");
		else System.out.println("No"); S[0] == S[3] S[0] S 0 S[3] S 3 System.out.println("No") System.out.println System.out System System.out "No" if(S[0] == S[1] && S[2] == S[3]) System.out.println("Yes");
		else System.out.println("No"); S[0] == S[1] && S[2] == S[3] S[0] == S[1] S[0] S 0 S[1] S 1 S[2] == S[3] S[2] S 2 S[3] S 3 System.out.println("Yes") System.out.println System.out System System.out "Yes" 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();
		sc.close();
		Arrays.sort(S);
		if(S[0] == S[3]) System.out.println("No");
		else if(S[0] == S[1] && S[2] == S[3]) 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();
		sc.close();
		Arrays.sort(S);
		if(S[0] == S[3]) System.out.println("No");
		else if(S[0] == S[1] && S[2] == S[3]) 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();
		sc.close();
		Arrays.sort(S);
		if(S[0] == S[3]) System.out.println("No");
		else if(S[0] == S[1] && S[2] == S[3]) System.out.println("Yes");
		else System.out.println("No");
	}
}