题解 | #截取字符串#

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 in = new Scanner(System.in);
        StringBuilder sb = new StringBuilder(in.next());
        int k = in.nextInt();
        String result = sb.substring(0, k);
        System.out.println(result);
    }
}