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;
typedef long long ll;
const ll MOD = 1e9+7;

int main(void){
	ll a,b,c,d;
	cin>>a>>b>>c>>d;
	ll ans = 0;
	ans = abs(b-a)+1;
	ll tmp = 0;
	tmp += (b/c)-((a-1)/c);
	tmp += (b/d)-((a-1)/d);

	 ll x = c * d;

	  if(c<d){
	    ll tmp2 = c;
	    c = d;
	    d = tmp2;
	  }

	  ll r = c % d;
	  while(r!=0){
	    c = d;
	    d = r;
	    r = c % d;
	  }
	  ll lcm = x/d;
	 // cout<<lcm<<endl;
	  tmp -= ((b/lcm)-((a-1)/lcm));
	  //cout<<tmp<<endl;
	  cout<<ans-tmp<<endl;
}