import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        String S;
        Scanner sc = new Scanner(System.in);
        S = sc.nextLine();
        int count = 0;
        for(int i  = 1 ; i < S.length() ; i++)
        {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        }
        System.out.println(count == 2 ? "No" : "Yes");
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        String S;
        Scanner sc = new Scanner(System.in);
        S = sc.nextLine();
        int count = 0;
        for(int i  = 1 ; i < S.length() ; i++)
        {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        }
        System.out.println(count == 2 ? "No" : "Yes");
    }
} Main public static void main(String[] args) {
        String S;
        Scanner sc = new Scanner(System.in);
        S = sc.nextLine();
        int count = 0;
        for(int i  = 1 ; i < S.length() ; i++)
        {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        }
        System.out.println(count == 2 ? "No" : "Yes");
    } main {
        String S;
        Scanner sc = new Scanner(System.in);
        S = sc.nextLine();
        int count = 0;
        for(int i  = 1 ; i < S.length() ; i++)
        {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        }
        System.out.println(count == 2 ? "No" : "Yes");
    } String S; S Scanner sc = new Scanner(System.in); sc new Scanner(System.in) S = sc.nextLine() S sc.nextLine() sc.nextLine sc int count = 0; count 0 for(int i  = 1 ; i < S.length() ; i++)
        {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        } int i  = 1 ; int i  = 1 ; i 1 i < S.length() i S.length() S.length S i++ i++ i {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        } {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        } if(S.charAt(0) == S.charAt(i))
            {
                count++;
            } S.charAt(0) == S.charAt(i) S.charAt(0) S.charAt S 0 S.charAt(i) S.charAt S i {
                count++;
            } count++ count System.out.println(count == 2 ? "No" : "Yes") System.out.println System.out System System.out count == 2 ? "No" : "Yes" count == 2 count 2 "No" "Yes" String[] args args public class Main {
    public static void main(String[] args) {
        String S;
        Scanner sc = new Scanner(System.in);
        S = sc.nextLine();
        int count = 0;
        for(int i  = 1 ; i < S.length() ; i++)
        {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        }
        System.out.println(count == 2 ? "No" : "Yes");
    }
} public class Main {
    public static void main(String[] args) {
        String S;
        Scanner sc = new Scanner(System.in);
        S = sc.nextLine();
        int count = 0;
        for(int i  = 1 ; i < S.length() ; i++)
        {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        }
        System.out.println(count == 2 ? "No" : "Yes");
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        String S;
        Scanner sc = new Scanner(System.in);
        S = sc.nextLine();
        int count = 0;
        for(int i  = 1 ; i < S.length() ; i++)
        {
            if(S.charAt(0) == S.charAt(i))
            {
                count++;
            }
        }
        System.out.println(count == 2 ? "No" : "Yes");
    }
}
