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: Accepted)

#include <iostream>
#include <iomanip>
#include <bits/stdc++.h>
#include <vector>
#include <iterator>
#include <boost/math/common_factor.hpp>
#include <string>
#define pan(i,n) for(int i=0;i<n;i++)
#define ll long long int
#define vi vector<int>
#define pb push_back
#define INF 1e9+7
#define PI 3.141592653
using namespace std;

ll f(ll a,ll b , ll x){
    if(a%x==0)
        return (b/x)-(a/x)+1;
    else 
        return (b/x)-(a/x);
}

int main(){
    ll a,b,c,d;
    cin>>a>>b>>c>>d;
    ll lcm=boost::math::lcm(c,d);
    ll ans=(b-a+1)+f(a,b,lcm)-f(a,b,c)-f(a,b,d);
    cout<<ans;
}