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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define all(a) a.begin(),a.end()
#define P pair<long long,long long>
#define double long double
using namespace std;
signed main(){
  string a;
  cin>>a;
  int b=0;
  rep(i,a.size()){
  rep(j,a.size()){
    if(a.at(i)==a.at(j))
      b++;
  }
  }
  bool c=true;
  if(b>a.size())
    c=false;
  if(c)
    cout<<"yes";
  else
    cout<<"no";
  }