import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;

/*
Минимальный байт
*/

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

        FileInputStream fileInputStream = new FileInputStream(string);
        byte min = Byte.MIN_VALUE;

        while (fileInputStream.available() > 0) {
            int data = fileInputStream.read();

            if (data <= min) {

                min = (byte) data;


            }
        }
        fileInputStream.close();
        System.out.println(min);

    }
}