100481: [AtCoder]ABC048 B - Between a and b ...

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.