/* 
INPUT FILE, grades.dat:
12 15 7 19 8 20 16 18 18 0 15 12 15 10 18

EXPECTED OUTPUT:
Grade changed by 3
Grade changed by -8
Grade changed by 12
Grade changed by -11
Grade changed by 12
Grade changed by -4
Grade changed by 2
Grade changed by 0
Grade changed by -18
Grade changed by 15
Grade changed by -3
Grade changed by 3
Grade changed by -5
Grade changed by 8
*/

import java.io.*;

public class Difference {
    public static void main(String[] args) throws FileNotFoundException {
        Scanner input = new Scanner(new File("grades.dat"));
        int num1;
        int num2 = input.nextInt();
        while (input.hasNextInt()) {
            num1 = num2;
            num2 = input.nextInt();
            System.out.println("Grade changed by " + (num2 - num1));
        }
    }
}