Делаю задачу так 
package com.javarush.task.task01.task0140;

import java.util.Scanner;

/*
Выводим квадрат числа
*/

public class Solution {
    public static void main(String[] args) {
        int a;
        Scanner scan = new Scanner(System.in);
         a = scan.nextInt();
        System.out.print(a*a);
    }
}
И мне выдает гору ошибок. Почему? 
java.util.NoSuchElementException
	at java.util.Scanner.throwFor(Scanner.java:862)
	at java.util.Scanner.next(Scanner.java:1485)
	at java.util.Scanner.nextInt(Scanner.java:2117)
	at java.util.Scanner.nextInt(Scanner.java:2076)
	at com.javarush.task.task01.task0140.Solution.main(Solution.java:13)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.javarush.task.common.model.execution.ExecuteService.callMainMethod(ExecuteService.java:78)
	at com.javarush.task.common.model.execution.ExecuteService.execute(ExecuteService.java:102)
	at com.javarush.task.app.execution.ExecutionService.execute(ExecutionService.java:76)
	at com.javarush.task.app.execution.ExecutionService.main(ExecutionService.java:213)
	at com.javarush.task.app.MainApplication.main(MainApplication.java:49)