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


	static char[][] map;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);			//文字の入力
		String n = sc.next();
		char[] cs = n.toCharArray();
		Arrays.sort(cs);
		if(cs[0] == cs[1] && cs[1] != cs[2] && cs[2] == cs[3]){
			System.out.println("Yes");
			return;
		}
		System.out.println("No");



	}



	static int gcd(int a,int b){				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}
	static long gcd(long a,long b){
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}



	static long lcm (long a, long b) {
		long g = gcd(a,b);
		return a/g*b;
	}




}



class Pair implements Comparable{
	int from;
	int end;
	@Override
	public int compareTo(Object other) {
		Pair otherpair = (Pair)other;

		return   end- otherpair.end;
	}







	static int find(int index,int current,int[] students,int ans,int[][] memo){
		if(current == index){
			return 1;
		}

		if(memo[current][index] != 0){
			return memo[current][index];
		}

		memo[current][index] = find(index, students[current]-1, students, ans+1, memo)+1;

		return memo[current][index];
	}



	static int gcd(int a,int b){				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}
	static long gcd(long a,long b){
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}



	static long lcm (long a, long b) {
		long g = gcd(a,b);
		return a/g*b;
	}




}



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


	static char[][] map;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);			//文字の入力
		String n = sc.next();
		char[] cs = n.toCharArray();
		Arrays.sort(cs);
		if(cs[0] == cs[1] && cs[1] != cs[2] && cs[2] == cs[3]){
			System.out.println("Yes");
			return;
		}
		System.out.println("No");



	}



	static int gcd(int a,int b){				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}
	static long gcd(long a,long b){
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}



	static long lcm (long a, long b) {
		long g = gcd(a,b);
		return a/g*b;
	}




} Main static char[][] map; map public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);			//文字の入力
		String n = sc.next();
		char[] cs = n.toCharArray();
		Arrays.sort(cs);
		if(cs[0] == cs[1] && cs[1] != cs[2] && cs[2] == cs[3]){
			System.out.println("Yes");
			return;
		}
		System.out.println("No");



	} main {
		Scanner sc = new Scanner(System.in);			//文字の入力
		String n = sc.next();
		char[] cs = n.toCharArray();
		Arrays.sort(cs);
		if(cs[0] == cs[1] && cs[1] != cs[2] && cs[2] == cs[3]){
			System.out.println("Yes");
			return;
		}
		System.out.println("No");



	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String n = sc.next(); n sc.next() sc.next sc char[] cs = n.toCharArray(); cs n.toCharArray() n.toCharArray n Arrays.sort(cs) Arrays.sort Arrays cs if(cs[0] == cs[1] && cs[1] != cs[2] && cs[2] == cs[3]){
			System.out.println("Yes");
			return;
		} cs[0] == cs[1] && cs[1] != cs[2] && cs[2] == cs[3] cs[0] == cs[1] && cs[1] != cs[2] && cs[2] == cs[3] cs[0] == cs[1] cs[0] cs 0 cs[1] cs 1 cs[1] != cs[2] cs[1] cs 1 cs[2] cs 2 cs[2] == cs[3] cs[2] cs 2 cs[3] cs 3 {
			System.out.println("Yes");
			return;
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" return; System.out.println("No") System.out.println System.out System System.out "No" String[] args args static int gcd(int a,int b){				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	} gcd {				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	} if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		} b == 0 b 0 {
			return a;
		} return a; a {
			return gcd(b, a%b);
		} return gcd(b, a%b); gcd(b, a%b) gcd b a%b a b int a a int b b static long gcd(long a,long b){
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	} gcd {
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	} if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		} b == 0 b 0 {
			return a;
		} return a; a {
			return gcd(b, a%b);
		} return gcd(b, a%b); gcd(b, a%b) gcd b a%b a b long a a long b b static long lcm (long a, long b) {
		long g = gcd(a,b);
		return a/g*b;
	} lcm {
		long g = gcd(a,b);
		return a/g*b;
	} long g = gcd(a,b); g gcd(a,b) gcd a b return a/g*b; a/g*b a/g a g b long a a long b b class Pair implements Comparable{
	int from;
	int end;
	@Override
	public int compareTo(Object other) {
		Pair otherpair = (Pair)other;

		return   end- otherpair.end;
	}







	static int find(int index,int current,int[] students,int ans,int[][] memo){
		if(current == index){
			return 1;
		}

		if(memo[current][index] != 0){
			return memo[current][index];
		}

		memo[current][index] = find(index, students[current]-1, students, ans+1, memo)+1;

		return memo[current][index];
	}



	static int gcd(int a,int b){				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}
	static long gcd(long a,long b){
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}



	static long lcm (long a, long b) {
		long g = gcd(a,b);
		return a/g*b;
	}




} Pair int from; from int end; end @Override
	public int compareTo(Object other) {
		Pair otherpair = (Pair)other;

		return   end- otherpair.end;
	} compareTo {
		Pair otherpair = (Pair)other;

		return   end- otherpair.end;
	} Pair otherpair = (Pair)other; otherpair (Pair)other return   end- otherpair.end; end- otherpair.end end otherpair.end otherpair otherpair.end Object other other static int find(int index,int current,int[] students,int ans,int[][] memo){
		if(current == index){
			return 1;
		}

		if(memo[current][index] != 0){
			return memo[current][index];
		}

		memo[current][index] = find(index, students[current]-1, students, ans+1, memo)+1;

		return memo[current][index];
	} find {
		if(current == index){
			return 1;
		}

		if(memo[current][index] != 0){
			return memo[current][index];
		}

		memo[current][index] = find(index, students[current]-1, students, ans+1, memo)+1;

		return memo[current][index];
	} if(current == index){
			return 1;
		} current == index current index {
			return 1;
		} return 1; 1 if(memo[current][index] != 0){
			return memo[current][index];
		} memo[current][index] != 0 memo[current][index] memo[current] memo current index 0 {
			return memo[current][index];
		} return memo[current][index]; memo[current][index] memo[current] memo current index memo[current][index] = find(index, students[current]-1, students, ans+1, memo)+1 memo[current][index] memo[current] memo current index find(index, students[current]-1, students, ans+1, memo)+1 find(index, students[current]-1, students, ans+1, memo) find index students[current]-1 students[current] students current 1 students ans+1 ans 1 memo 1 return memo[current][index]; memo[current][index] memo[current] memo current index int index index int current current int[] students students int ans ans int[][] memo memo static int gcd(int a,int b){				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	} gcd {				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	} if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		} b == 0 b 0 {
			return a;
		} return a; a {
			return gcd(b, a%b);
		} return gcd(b, a%b); gcd(b, a%b) gcd b a%b a b int a a int b b static long gcd(long a,long b){
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	} gcd {
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	} if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		} b == 0 b 0 {
			return a;
		} return a; a {
			return gcd(b, a%b);
		} return gcd(b, a%b); gcd(b, a%b) gcd b a%b a b long a a long b b static long lcm (long a, long b) {
		long g = gcd(a,b);
		return a/g*b;
	} lcm {
		long g = gcd(a,b);
		return a/g*b;
	} long g = gcd(a,b); g gcd(a,b) gcd a b return a/g*b; a/g*b a/g a g b long a a long b b Comparable
import java.util.Arrays;
import java.util.Scanner;
class Main{


	static char[][] map;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);			//文字の入力
		String n = sc.next();
		char[] cs = n.toCharArray();
		Arrays.sort(cs);
		if(cs[0] == cs[1] && cs[1] != cs[2] && cs[2] == cs[3]){
			System.out.println("Yes");
			return;
		}
		System.out.println("No");



	}



	static int gcd(int a,int b){				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}
	static long gcd(long a,long b){
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}



	static long lcm (long a, long b) {
		long g = gcd(a,b);
		return a/g*b;
	}




}



class Pair implements Comparable{
	int from;
	int end;
	@Override
	public int compareTo(Object other) {
		Pair otherpair = (Pair)other;

		return   end- otherpair.end;
	}







	static int find(int index,int current,int[] students,int ans,int[][] memo){
		if(current == index){
			return 1;
		}

		if(memo[current][index] != 0){
			return memo[current][index];
		}

		memo[current][index] = find(index, students[current]-1, students, ans+1, memo)+1;

		return memo[current][index];
	}



	static int gcd(int a,int b){				//最大公約数を返す
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}
	static long gcd(long a,long b){
		if(b == 0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}



	static long lcm (long a, long b) {
		long g = gcd(a,b);
		return a/g*b;
	}




}




