题解 | #单组_补充前导零#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
         Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        String s = String.valueOf(n);
        if (s.length() < 9) {
            StringBuilder zeros = new StringBuilder();
            for (int i = 0; i < 9 - s.length(); i++) {
                zeros.append("0");
            }
            s = zeros.toString() + s;
        }
        System.out.println(s.substring(0, 9));
        scanner.close();
    }
}