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;
int main(){
	unsigned long long a,b,c,d,c1=0,c2=0,cd=0,res=0;
	cin>>a>>b>>c>>d;
	res=b-a+1;
	if (a%c==0) c1=a/c;
	else c1=a/c+1;
	c2=b/c;
	if (c2-c1+1>0) res-=(c2-c1+1);
	if (a%d==0) c1=a/d;
	else c1=a/d+1;
	c2=b/d;
	if (c2-c1+1>0) res-=(c2-c1+1);
	cd=c*d/__gcd(c,d);
	if (a%cd==0) c1=a/cd;
	else c1=a/cd+1;
	c2=b/cd;
	if (c2-c1+1>0) res+=(c2-c1+1);
	cout<<res;
	return 0;
}