Problem:
Score : 300 points

Problem Statement

You are given four integers A, B, C, and D. Find the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Constraints

1\leq A\leq B\leq 10^{18}

1\leq C,D\leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B C D

Output

Print the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Sample Input 1

4 9 2 3

Sample Output 1

2

5 and 7 satisfy the condition.

Sample Input 2

10 40 6 8

Sample Output 2

23

Sample Input 3

314159265358979323 846264338327950288 419716939 937510582

Sample Output 3

532105071133627368

Solution in C++14 (GCC 5.4.1) (judge verdict: Runtime Error)

/*
    g++ -std=c++14 -O2 -Wall a.cpp -o a && a
    g++ -std=c++14 -O2 -Wall a.cpp -o a && a < in.txt > out.txt
    */

//  io
#include <iostream>
//#include <fstream> //http://www.cplusplus.com/reference/fstream/fstream/
//#include <cstdio>
#include <iomanip> //http://www.cplusplus.com/reference/iomanip/
#include <limits>
//  util
#include <string>
#include <cstring>
#include <algorithm>
//#include <utility>
//#include <functional> //http://www.cplusplus.com/reference/functional/
//#include <cstdlib>
#include <cmath>
//#include <complex>
//#include <random>
//#include <bitset>
//  containers https://en.cppreference.com/w/cpp/container
#include <vector>
#include <queue>
#include <set>
//#include <map>
//#include <unordered_set>
//#include <unordered_map>
//  time
//#include <ctime>
//#include <chrono>
//                  https://en.cppreference.com/w/cpp/header/chrono
//                  http://www.cplusplus.com/reference/chrono/

using namespace std;
typedef vector<int> arri;
typedef vector<float> arrf;
typedef pair<int, int> pairi;
typedef long long ll;
typedef long double ld;
const int mod = 1e9 + 7;
const ll inf = 0x7fffffffffffffff;
const ll infneg = -0x7fffffffffffffff;

//file input routed to stdinout
/*
    std::ifineam inFile("input.txt");
    std::ofineam outFile("output.txt");
    std::cin.rdbuf(inFile.rdbuf());
    std::cout.rdbuf(outFile.rdbuf());
    */

int main()
{
    ll a, b, c, d;
    cin >> a >> b >> c >> d;

    ll divs = b / c - a / c + b / d - a / c;
    divs -= (b / (__gcd(c, d) / (c * d)) - a / (__gcd(c, d) / (c * d)));
    cout << divs;
}