import java.util.Scanner;

public class achievement {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入上次考试成绩：");
        int firstGrade = scanner.nextInt();
        System.out.println("请输入本次考试成绩：");
        int thisGrade = scanner.nextInt();
        double increase = (double) (thisGrade-firstGrade)/firstGrade;
        System.out.printf("%.2f",increase*100);
        System.out.print("%");

    }
}