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