public class Solution {
    public static void main(String[] args) throws Exception {
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        FileInputStream fileInputStream = new FileInputStream(reader.readLine())){

            int[] arrayOfBytes = new int[256];

            while (fileInputStream.available() > 0){
                arrayOfBytes[fileInputStream.read()]++;
            }

            int min = 255;

            for (int x = 0; x < arrayOfBytes.length; x++) {
                if(x > 1 & x < min){
                    min = x;
                }
            }

            for (int x = 0; x < arrayOfBytes.length; x++) {
//                System.out.print(arrayOfBytes[x] + " *** " + x + " ");
                if (arrayOfBytes[x] == min){
                    System.out.print(x + " ");
                }
            }

        } catch (IOException e){
            e.printStackTrace();
        }
    }
}