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>
using namespace std;
int gcd(int c, int d) { 
   if (d == 0) 
      return c; 
   return gcd(d, c % d);  
} 

int main() {
         long long a,b,c,d;
         cin>>a>>b>>c>>d;
         long long l,m,lcm;
	l=c*d;
	m=gcd(c,d);
	lcm=l/m;
	long long divc=b/c-(a-1)/c;
	long long divd=b/d-(a-1)/d;
	long long res= b/lcm-(a-1)/lcm;
	cout<< (b-a+1)-divc-divd+res<<endl;
	return 0;
}