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 Go (1.14.1) (judge verdict: Runtime Error)

package main

import (
	"fmt"
)

func main() {
	var a, b, x int
	fmt.Scanf("%d %d %d", &a, &b, &x)

	chunk := (b - a) / x
	if chunk >= 1 && a%x == 0 {
		fmt.Printf("%d\n", chunk+1)
	} else if chunk >= 1 {
		fmt.Printf("%d\n", chunk)
	} else if x%a <= (b - a) {
		fmt.Printf("%d\n", 1)
	} else {
		fmt.Printf("%d\n", 0)
	}

}