Help me in solving BC106 problem

help
,
1

My issue

Main.java:3: error: class longsum is public, should be declared in a file named longsum.java
public class longsum {
^
1 error

My code

import java.util.*;

public class longsum {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
            int n = scan.nextInt();
            long a[] = new long[n];
            Long sum = 0L;
            for (int i = 0; i < n; i++) {
                a[i] = scan.nextLong();
                sum += a[i];
            }
        System.out.print(sum);
        }  
}

Problem Link: Long Long Sum Practice Coding Problem - CodeChef