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)

#include<stdio.h>

int main(void)
{
  char str[27] = {0};
  char c;
  int flag = 1;//真偽値的な
  int cnt = 0;//一つのアルファベットがstrに含まれる回数
  int i = 0;//配列のインデックスを動かす

  scanf("%s", str);

  for(c = 'a'; c <= 'z'; c++){
    while(str[i] != '\0'){
      if(str[i] == c){
        cnt++;
      }
      i++;
    }
    //同じ文字が2回以上出てきたらnoなので
    if(cnt > 1){
      flag = 0;
      break;
    }
    cnt = 0;
    i = 0;
  }

  if(flag == 1){
    printf("yes\n");
  }else{
    printf("no\n");
  }

  return 0;
}