﻿ ABC048 B - Between a and b ... - Atcoder

# Home

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.