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 Python (3.8.2) (judge verdict: Accepted)

a, b, x = 4, 8, 3
a, b, x = 0, 5, 1
a, b, x = 9, 9, 2
a, b, x = 1, 1000000000000000000, 3

a, b, x = map(int,input().split())


def calculate(a, b, x):
    s1 = (a - 1) // x

    if s1 < 0:
        s1 = 0
    else:
        s1 += 1
    s2 = b // x + 1

    print(s2 - s1)


calculate(a, b, x)