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 <cstring>
#include <algorithm>
#define LL long long
using namespace std;
inline LL Gcd(LL a,LL b)
{
	if(a%b==0)return b;
	return Gcd(b,a%b);
}
inline LL Calc(LL a,LL b,LL num)
{
	return num-num/a-num/b+num/a*Gcd(a,b)/b;
}
int main(void)
{
	LL A,B,C,D;
	scanf("%lld%lld%lld%lld",&A,&B,&C,&D);
	printf("%lld\n",Calc(C,D,B)-Calc(C,D,A-1));
	return 0;
}