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 <iostream>
#include <iomanip>
#include <utility>
#include <cmath>
#include <random>
#include <vector>
#include <tuple>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <string>
#include <algorithm>
using namespace std;

#define rep(i,n) for(int i = 0; i<n; ++i)
#define REP(i,n) for(int i = 1; i<=n; ++i)
#define all(x) begin(perm),end(perm)
#define showall(obj) for(auto x:obj)cout<<x<<endl;
typedef long long ll;
typedef pair<int,int> ip;
typedef pair<ll,ll> lp;
typedef vector<int> vint;
typedef vector<ll> vll;
const int inf = 100100100;
const ll INF = 1LL<<60;
const int MOD = (int)1e9 + 7;

int main(){
    string s; cin>>s;
    set<char> m;
    rep(i,s.size()){
        if(!m.count(s[i]))m.insert(s[i]);
        else {cout<<"no"<<endl;return 0;}
    }
    cout<<"yes"<<endl ;return 0;
}