using System;
class Program
{
static bool contains_unique_chars(string s) {
char[] arr = s.ToCharArray();
Array.Sort(arr);
for (int i = 0; i < arr.Length - 1; i++) {
if (arr[i] == arr[i + 1])
return false;
}
return true;
}
static void Main() {
string s = "abcde";
if (contains_unique_chars(s)) {
Console.Write("yes");
}
else {
Console.Write("no");
}
}
}
/*
run:
yes
*/