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<cstdio>
#include<algorithm>
using namespace std;
typedef long long ll;
ll a,b,c,d;

int gcd(int a,int b)
{
	if(b == 0) return a;
	return gcd(b,a%b);
}
int main(void)
{
 	scanf("%lld %lld %lld %lld",&a,&b,&c,&d);
 	ll t1 = b/c-(a-1)/c;
 	ll t2 = b/d-(a-1)/d;
// 	ll g = c*d/__gcd(c,d);
	ll g = c*d/gcd(c,d);
 	ll t3 = b/g-(a-1)/g;
 	printf("%lld",(b-a+1)-t1-t2+t3);
	return 0;
}