#include <bits/stdc++.h>
using namespace std;
int main() {
    int judge = 0;
    string str;
    cin >> str;
    
    for ( int i = 0 ; i < str.size()-1 ; i++ ) {
        for ( int j = i+1 ;j < str.size() ; j++ ) {
            if ( str.at(i) == str.at(j) ) {
                cout << "No" << endl;
                judge = 1;
                break;
            }
            
        }
    }
    
    if ( judge == 0 ) {
        
        cout << "Yes" << endl;
    }
}