package Oct_24;
import java.io.IOException;
import java.io.InputStreamReader;

public class T_1769 {
    public static void main(String[] args) throws IOException {
        InputStreamReader is = new InputStreamReader(System.in);
            char c[] = new char[(int) 4e+5 + 1];
            int k = 0;
            c[k] = (char)is.read();
            while(is.ready()){
                k++;
                c[k] = (char) is.read();
            }
            k--;
            int t = 0;
            int [] a = new int [100001];
            for (int i = 1; i <=4; i++) {
                for (int j = 0; j+i <= k; j++) {
                    String s = (new String(c,j,i));
                    a[t] = Integer.parseInt(s);
                    t++;
                }
            }
            boolean f[] = new boolean [400001];
            for (int i = 0; i < t; i++) {
                f[a[i]]= true;
            }
            for (int i = 1; i < f.length; i++) {
                if(!f[i]){
                    System.out.println(i);
                    return;
                }
            }
    }
}

Edited by author 24.10.2011 19:29

Edited by author 24.10.2011 19:29