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<cstdio>
#include<algorithm>
#include<iostream>
#include<string>
#include<vector>
#include<stack>
#include<bitset>
#include<cstdlib>
#include<cmath>
#include<set>
#include<list>
#include<deque>
#include<map>
#include<queue>
using namespace std;
typedef long long ll;
const double PI = acos(-1.0);
const double eps = 1e-6;
const int mod = 1e9+7;
const int maxn = 200005;
int T,n,m;
ll a[maxn];
int gcd(int a,int b)
{
    return b>0?gcd(b,a%b):a;
}
int main() {
	ll x,y,z,w;
	cin>>x>>y>>z>>w;
	ll sum = z+w;
	z = max(z,w);
	w = sum-z;
	ll t = z*w/gcd(z,w);
	ll x1 = x/z,x2=x/w,x3=x/t;
	ll y1 = y/z,y2=y/w,y3=y/t;
	if(x%z==0)
		x1--;
	if(x%w==0)
		x2--;
	if(x%t==0)
		x3--;
	cout<<y-x+1-(y1-x1)-(y2-x2)+(y3-x3)<<endl;
    return 0;
}