Problem:
Score : 200 points

Problem Statement

You are given nonnegative integers a and b (a ≤ b), and a positive integer x.
Among the integers between a and b, inclusive, how many are divisible by x?

Constraints

0 ≤ a ≤ b ≤ 10^{18}

1 ≤ x ≤ 10^{18}

Input

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

a b x

Output

Print the number of the integers between a and b, inclusive, that are divisible by x.

Sample Input 1

4 8 2

Sample Output 1

3

There are three integers between 4 and 8, inclusive, that are divisible by 2: 4, 6 and 8.

Sample Input 2

0 5 1

Sample Output 2

6

There are six integers between 0 and 5, inclusive, that are divisible by 1: 0, 1, 2, 3, 4 and 5.

Sample Input 3

9 9 2

Sample Output 3

0

There are no integer between 9 and 9, inclusive, that is divisible by 2.

Sample Input 4

1 1000000000000000000 3

Sample Output 4

333333333333333333

Watch out for integer overflows.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		ArrayList<BigInteger> num = new ArrayList<BigInteger>();
		ArrayList<String> param = new ArrayList<String>();
		int system = 0; // 文字の空白区切り 0:ON 1:OFF

		while (sc.hasNext()) {
			if (sc.hasNextBigInteger()) {
				num.add(sc.nextBigInteger());
			} else {
				if (system == 0)
					param.add(sc.next());
				if (system == 1)
					param.add(sc.nextLine());
			}
		}
		Method(num, param);
	}

	static void Method(ArrayList<BigInteger> num, ArrayList<String> param) {
		
		System.out.println(num.get(1).divide(num.get(2)).subtract(num.get(0).subtract(BigInteger.ONE).divide(num.get(2))));
	}
}