Problem:
Score : 100 points

Problem Statement

There are N children in AtCoder Kindergarten. Mr. Evi will arrange the children in a line, then give 1 candy to the first child in the line, 2 candies to the second child, ..., N candies to the N-th child. How many candies will be necessary in total?

Constraints

1≦N≦100

Input

The input is given from Standard Input in the following format:

N

Output

Print the necessary number of candies in total.

Sample Input 1

3

Sample Output 1

6

The answer is 1+2+3=6.

Sample Input 2

10

Sample Output 2

55

The sum of the integers from 1 to 10 is 55.

Sample Input 3

1

Sample Output 3

1

Only one child. The answer is 1 in this case.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.util.*;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
	
		int N = sc.nextInt();
		
		int[] arr = new int[N];
		int sum = 0;
		
		for(int i = 0 ; i < N ; i++){
			arr[i] = sc.nextInt();
			sum += arr[i];
		}

		sc.close();
		
		int aver = sum / N;
		
		int value = calculateDiff(arr, aver);
	
		value = Math.min( calculateDiff(arr, aver + 1), value );
		
		System.out.println(value);
	}

	static int calculateDiff(int[] arr, int aver) {
		int diff = 0;
		
		for(int i = 0 ; i < arr.length ; i++){
			diff += ((arr[i] - aver) * (arr[i] - aver));
		}
		
		return diff;
	}
}