用Java提交poj的细节问题

import java.util.Scanner;public class Poj1003 {//错误public class Main {//正确……不知道什么鬼public static void main(String arg[]){    double a[]=new double[1000];    for(int i=2;i<990;i++){        a[i]=a[i-1]+(1.0/i);    }    Scanner reader=new Scanner(System.in);    double k=reader.nextDouble();    while(Math.abs(k-0.0)>0.0001)    {        int mid,left=2,right=989;        while(left<=right)        {            mid=(left+right)/2;            if(a[mid]>k || Math.abs(a[mid]-k)<0.0001) right=mid-1;            else if(a[mid]<k) left=mid+1;        }        System.out.println(left-1+" card(s)");        k=reader.nextDouble();    }}}

错误信息为：Class poj1003 is public, should be declared in a file named “poj1003.java”