Problem:
Score : 200 points

Problem Statement

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.

Sample Input 1

uncopyrightable

Sample Output 1

yes

Sample Input 2

different

Sample Output 2

no

Sample Input 3

no

Sample Output 3

yes

Solution in C (GCC 5.4.1) (judge verdict: Accepted)

int main(){
    char str[27]={'\0'};
    scanf("%s",str);
    int flag=0;
    for(int i=0;i<strlen(str);i++){
        for(int j=i+1;j<strlen(str);j++)
        if(str[i]==str[j]){printf("no");flag=1;break;}
        if(flag==1)break;
    }
    if(flag==0)printf("yes");
    return 0;
    }