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 Rust (1.42.0) (judge verdict: Accepted)

#![allow(dead_code,unused_variables,unused_imports)]
use proconio::{fastout, input};
use proconio::marker::Chars;
use std::cmp::max;

#[fastout]
fn main() {
    input!{
        a:usize,
        b:usize,
        x:usize,
    }

    let n_max : i64 = (b/x) as i64;
    let n_min : i64 = if a == 0 { -1 } else {((a - 1)/x) as i64}; 

    println!("{}",n_max-n_min);

}