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>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#define ll long long
#define rep(i,n) for(ll i=0;i<(n);i++)
#define max(p,q) ((p)>(q)?(p):(q))
#define min(p,q) ((p)<(q)?(p):(q))
#define chmax(a,b) ((a)=(a)>(b)?(a):(b))
#define chmin(a,b) ((a)=(a)<(b)?(a):(b))
#define abs(p) ((p)>=(0)?(p):(-(p)))
#define MOD 1000000007
ll powll(ll a,ll b){ll r=1;rep(i,b){r*=a;}return r;}
#define swap(a,b) do{ll w=(a);(a)=(b);(b)=w;}while(0)
#define swapd(a,b) do{double w=(a);(a)=(b);(b)=w}while(0)
#define in(a) scanf("%lld", &(a))
#define in2(a,b) scanf("%lld %lld",&(a),&(b))
#define in3(a,b,c) scanf("%lld %lld %lld",&(a),&(b),&(c))
#define ind(a) scanf("%lf", &(a))
#define ins(a) scanf("%s", (a))
#define inc(a) scanf("%c", &(a))
#define put(a) printf("%lld\n", (a))
#define putd(a) printf("%.15f\n", (a))
//      puts(a) printf("%s\n", a) 文字はこっち
//your code here!
int main(void){
    ll alph[26]={0}, i=0;
    char S[30];
    ins(S);
    while(S[i]!='\0'){
        if(alph[S[i]-'a']){
            puts("no");
            return 0;
        }
        alph[S[i++]-'a']++;
    }
    puts("yes");
    return 0;
}