#include<bits/stdc++.h>
using namespace std;
char s[9999];
int main()
{
    cin >> s;
    int N = strlen(s);
    sort(s, s+N);
    if(unique(s, s+N)==s+N)
        puts("yes");
    else
        puts("no");
}
### Prompt

Create a solution in Cpp for the following problem:

You are given a string S consisting of lowercase English letters. Determine whether all the characters in S are different.

Constraints

* 2 ≤ |S| ≤ 26, where |S| denotes the length of S.
* S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:


S


Output

If all the characters in S are different, print `yes` (case-sensitive); otherwise, print `no`.

Examples

Input

uncopyrightable


Output

yes


Input

different


Output

no


Input

no


Output

yes

### Response

```cpp
#include<bits/stdc++.h>
using namespace std;
char s[9999];
int main()
{
    cin >> s;
    int N = strlen(s);
    sort(s, s+N);
    if(unique(s, s+N)==s+N)
        puts("yes");
    else
        puts("no");
}
```