백준 - 8진수,2진수(1212)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String s = br.readLine();
        StringBuilder sb = new StringBuilder();
        String[] b = {"000","001","010","011","100","101","110","111"};

        for(int i=0;i<s.length();i++) {
            int a =  s.charAt(i)-'0';

            sb.append(b[a]);
        }

        if(s.equals("0")) System.out.println(s);
        else{
            while(sb.charAt(0) == '0') sb = new StringBuilder(sb.substring(1));
            System.out.println(sb);
        }
    }
}