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 <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define ll long long
using namespace std;
bool comp(pair<int,int> a, pair<int,int> b) {
	if(a.second == b.second) {
		return a.first<b.first;
	}
	return a.second<b.second;
}
int main() {
	ll a,b,c,d;
	cin>>a>>b>>c>>d;
	ll x = b/c+b/d-b/((c*d)/__gcd(c,d));
	ll y = (a-1)/c+(a-1)/d-(a-1)/((c*d)/__gcd(c,d));
	cout<<b-a+1-x+y;
	return 0;
}