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().split("");
        Arrays.sort(s);
        if (s[0].equals(s[1]) && s[2].equals(s[3]) && !s[0].equals(s[2])) {
            System.out.println("Yes");
            return;
        }
        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);
        String[] s = sc.next().split("");
        Arrays.sort(s);
        if (s[0].equals(s[1]) && s[2].equals(s[3]) && !s[0].equals(s[2])) {
            System.out.println("Yes");
            return;
        }
        System.out.println("No");
    }

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

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

} public class Main {

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

}
