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<cstdio>
#include<cmath>
#include<string>
#include<iostream>
#include<algorithm>
#include<utility>
#include<vector>
#include<map>
#include<set>
#include<limits>
#include<bitset>
#include<array>
#include<numeric>
#include<iomanip>
#include<functional>
#include<deque>

using namespace std;
typedef long long int ll;

#define C cout<<
#define E <<endl

ll n,m,a,b,c,x,y,z,aa[200010],ab[200010],ac[1010][1010];
bool r,ra,rb,rc;
string s,sa,sb,sc;
char ca,cb,cc,cd[1010][1010];
vector<ll> va,vb,vc[3];

int main(){
    cin>>a>>b>>c;
    C b/c-(a-1)/c E;
}