Array 问题

[sevendays]

让用户输入学生总数和学生的成绩，程序得出学生的等级并且显示出来。
Grade is "A" if score is >= best -10
Grade is "B" if score is >= best -20
Grade is "C" if score is >= best -30
Grade is "D" if score is >= best -40
Grade is "F" otherwise.
示例如下
Enter the number of students: 4
Enter 4 scores:
40
55
70
58
RESULTS ARE DISPLAYED BELOW:
Student 1 score is 40 and grade is C
Student 2 score is 55 and grade is B
Student 3 score is 70 and grade is A
Student 3 score is 58 and grade is B
我写的代码如下，但是无法运行，不知道为什么

import java.util.Scanner;
public class grades {
	public static void main(String[] args){
		Scanner input=new Scanner(System.in);
		System.out.print("Enter the number of students:");
		int  z=input.nextInt();
		double[] scores=new double[z];
		System.out.print("Enter"+scores.length+"scores:");
		for (int i=0;i<scores.length;i++){
			
			scores[i]=input.nextDouble();
			
		}
		for (int i=0;i<scores.length;i++){
			if (scores[i]>=90)
				System.out.println("Student "+i+"score is"+scores[i]+
						"and grad is A");
			else if (scores[i]>=80)
				System.out.println("Student "+i+"score is"+scores[i]+
						"and grad is B");
			else if (scores[i]>=70)
				System.out.println("Student "+i+"score is"+scores[i]+
						"and grad is c");
			else if (scores[i]>=60)
				System.out.println("Student "+i+"score is"+scores[i]+
						"and grad is D");
			else
				System.out.println("Student "+i+"score is"+scores[i]+
						"and grad is F");

[sevendays]

哈哈 不好意思 我又试了一下 可以运行，乌龙了~~~

[菖蒲老先生]

类名最好用大写。。。

[成一粒]

怎么不能运行？