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;
#define ll long long int 

int main(){
 ll i,j,k;
  ll a,b,c,d;
  cin>>a>>b>>c>>d;
  a-=1;
  ll c1=a/c+a/d;
  c1-=(a/((c*d)/__gcd(c,d)));

  ll c2=b/c+b/d;
  c2-=(b/((c*d)/__gcd(c,d)));
  c2-=c1;
  ll len=b-a;
 // cout<<len<<" "<<c2<<"\n";
  len-=c2;
  cout<<len<<"\n";
}