import java.util.*;

class Solution {
       public static String hasUnique(String str) {
      int n = str.length();
		boolean count = true;
		int []s= new int[26];
		int []l= new int[26];
		for(int i=0;i<26;i++){
			s[i]=0;
			l[i]=0;
		}
	for(int i=0;i<n;i++){
		if(str.charAt(i)>='a' && str.charAt(i)<='z')s[str.charAt(i)-'a']++;
	}
		   for(int i=0;i<n;i++){
		if(str.charAt(i)>='A' && str.charAt(i)<='Z')l[str.charAt(i)-'A']++;
	}
		   for(int i=0;i<26;i++){
			   if(s[i]>1 || l[i]>1)count=false;
		   }
       if(count==true){
		  return ("Yes");
	   }
		else{
			return ("No");
		}
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str = sc.nextLine();
        Solution Obj = new Solution();
        System.out.println(Obj.hasUnique(str));
    }
}