#include<iostream>
#include<memory.h>
#include<string>
#include<sstream>

using namespace std;

int main(){

    string s,str;
    cin>>str;
    int arr[10];
    memset(arr,-1,sizeof(arr));

    stringstream ss;
    ss<<str[str.size()-1];
    s.append(ss.str());
    for(int i=str.size()-2;i>=0;i--){
        if(s.find(str[i])==s.npos){
            stringstream ss;
            ss<<str[i];
            s.append(ss.str());
        }
    }

    cout<<stoi(s);
    return 0;
}