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>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pi;

#define F first
#define S second
#define PB push_back
#define MK make_pair
#define REP(i, a, b) for (int i=a; i < b; i++)


bool sort_by(pi c, pi d){
	return c.S < d.S;
}

int main() {
	ll A, B,C,D;
	cin >> A >> B >> C >> D;
	
	--A;
	//ll ans = 0;
	ll minc = A/C;
	ll mind = A/D;
	ll mint = A/(C*D/__gcd(C,D));
	
	ll mac = B/C;
	ll mad = B/D;
	ll mat = B/(C*D/__gcd(C,D));
	
	ll not_ok = (mac+mad-mat) - (minc+mind-mint);
	cout << B-A-not_ok;

}