L1-032 Left-pad (20 分)

import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int n=scanner.nextInt();
String x=scanner.next();
char s=x.charAt(0);
String st=scanner.nextLine();
String line2=scanner.nextLine();
StringBuilder stringBuilder =new StringBuilder(line2);
int m=n-stringBuilder.length();
if(m>0){
for (int i = 0; i <m; i++) {
stringBuilder.insert(0,s);
}
System.out.println(stringBuilder);
}
else if (m<0){
System.out.println(stringBuilder.substring(stringBuilder.length()-n,stringBuilder.length()));
}
else if(m==0){
System.out.println(stringBuilder);
}
}
}