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 C (GCC 5.4.1) (judge verdict: Accepted)

//gcc -std=gnu11 -O2 -o a.out Main.c -lm
//http://abc048.contest.atcoder.jp/tasks/abc048_b
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdint.h>
#include <math.h>
#include <string.h>

int main(void)
{
#define N_MAX 100  //

	int i,j;
	long long a,b,x;
	int ret;


	//-------------------------------------
	//Input process
	//-------------------------------------
	ret = scanf("%lld%lld%lld", &a, &b, &x);

	//-------------------------------------
	//Calc process
	//-------------------------------------


	//-------------------------------------
	//Output process
	//-------------------------------------
	printf("%lld\n", (b/x) - ((a + x -1)/x) +1);
	return(0);
}