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 <string>
using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)
#define repp(i, n, m) for (int i = (int)(n); i < (int)(m); i++)
#define rrep(i, n, m) for (int i = n; i >= m; i--)
#define ALL(a) (a).begin(), (a).end()
#define p(a, b) printf(a, b);
#define c(s) cout << (s) << endl;
#define yes cout << "yes" << endl;
#define no cout << "no" << endl;
#define Yes cout << "Yes" << endl;
#define No cout << "No" << endl;
#define YES cout << "YES" << endl;
#define NO cout << "NO" << endl;
#define cyn(c) cout << (c ? "Yes" : "No") << endl;
#define cYN(c) cout << (c ? "YES" : "NO") << endl;
#define pyn(c) printf("%s\n", c ? "Yes" : "No");
#define pYN(c) printf("%s\n", c ? "YES" : "NO");
#define INF 1e18
typedef long long LL;
typedef unsigned long long ULL;
typedef pair<LL, LL> P;
template <class T>
bool contain(const std::string &s, const T &v)
{
  return s.find(v) != std::string::npos;
}
ULL mod = 1e9 + 7;

int main()
{
  string s;
  int al[26]={};
  cin >> s;
  rep(i,s.size())
  {
    al[s[i]-'a']++;
  }
  rep(i,26)
  {
    if(al[i]>=2){
      no;
      return 0;
    }
  }
  yes;
}