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>
using namespace std;

#define pi 3.141592654
#define fix(n) cout << fixed << setprecision(n)

#define rep(i,a,b) for(int i=a;i<b;i++)
#define ren(i,a,b) for(int i=a;i>=b;i--)

#define si(d)  scanf("%d",&d)
#define sll(d) scanf("%lld",&d)
#define pin(d) printf("%d\n",d)
#define pln(d) printf("%lld\n",d)
#define nl 	   printf("\n")

#define ll long long
#define ull unsigned long long

#define mp make_pair
#define pb push_back
#define fi first
#define se second

#define vi vector<int>
#define pii pair<int,int> 
#define piii pair<pair<int,int>,int> 

#define chalne_de continue
int mod=1000000007;
const int N = 1000005;

ll gcd(ll a , ll b)
{
    if ( b == 0)
    return a;
    return gcd( b, a % b);
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	//freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
	string s;
	cin >> s;
	int a[27] = {0};
	int l = s.length();
	for ( int i = 0; i < l; i++)
	{
		a[s[i]-'a']++;
	}
	for ( int i = 0; i < 26; i++)
	{
		if ( a[i] > 1)
		{
			cout << "no";
			return 0;
		}
	}
	cout << "yes";
	return 0;
}