p2745.java

import java.io.*;
import java.util.*;
public class p2745 {
    static String n;
    static int b;
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        n = st.nextToken();
        b = Integer.parseInt(st.nextToken());
        
        int ans = 0;
        for (int i = 0; i < n.length(); i++) {
            char c = n.charAt(i);
            if ('A' <= c && c <= 'Z') {
                ans = ans * b + ((c - 'A') + 10);
            } else {
                ans = ans * b + (c - '0');
            }
        }
        System.out.println(ans);
    }
        
}