#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;

int main()
{/*
    string num;
    cin>>num;
    int a[10]={0};
    for (int i=num.size()-1;i>=0;i--)
    {
        int index=((int) (num[i]));
        a[index]++;
        if (a[index]==1)
            cout<<index;
    }*/
    int m;
    cin>>m;
    int a[10]={0};
    do 
    {int n=m%10;
        m=m/10;
     a[n]++;
     if (a[n]==1)
     {
         cout<<n;
     }

    }while(m!=0);

}