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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;

int main()
{
	std::ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    long test=1;
// 	cin>>test;	
	while(test--)
	{
	    long a,b=0,c=0,k,i,n,j,mini,maxi,ans,q,sum,x,y,count=0,next,prev;
	   
	   // string s1,s2,s3;
	    cin>>a>>b>>n;
	    i=a;
	    while(i<=b)
	    {
	        if(a%n==0)
	        {
	            i+=n;
	            count++;
	        }
	        else i++;
	    }
	cout<<count;
    }
    
}