#include "bits/stdc++.h"
using namespace std;

int main()
{
    int num;
    cin >> num;
    int a[10] = {0};
    while (num > 0)
    {
        int t = num % 10;
        num = num / 10;
        if (a[t] == 0)
        {
            cout << t;
            a[t] = 1;
        }
    }
    return 0;
}

又是被虐的一题 啊啊啊啊