Calculate postage

Postage is calculated based on the weight of the mail and whether the user chooses expedited. Calculation rules: If the weight is within 1000 grams (including 1000 grams), the basic fee is 8 yuan. For the part that exceeds 1000 grams, an overweight fee of 4 yuan will be charged for every 500 grams, and the part less than 500 grams will be calculated as 500 grams; if the user chooses to rush, an extra 5 yuan will be charged.
Input
Enter a line containing an integer and a character, separated by a space, indicating the weight (in grams) and whether it is expedited. If the character is y, it means rush is selected; if the character is n, it means no rush.
Output
Output a line containing an integer representing postage.
Example input
1200 y

Sample output
17

import java.util.Scanner;
import java.io.*;  
public class Main {
    public static void main(String[] args) {
        int a,sum=0;
        String s;
        Scanner scan=new Scanner(System.in);
        a=scan.nextInt();
        s=scan.nextLine();
        if(s.equals(" y"))
        {
            if(a<=1000)
                sum=13;
            else if(a>1000)
                sum=((a-1000)/500+1)*4+8+5;     
        }
        else
        {
            if(a<=1000)
            {
                sum=8;
            }
            else
            {
                sum=((a-1000)/500+1)*4+8;
            }
        }
        System.out.println(sum);
        scan.close();
    }
}