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>
#define ll long long
#define pb push_back
#define mp make_pair
using namespace std;
#define maxv 100001
#define che 1LL<<32
#define mod 1000000007
int main()
{
    ll a,b,c,d;
    cin>>a>>b>>c>>d;
    ll lcm=(c*d)/(__gcd(c,d));
    ll ans=b/c+b/d-b/lcm;
    a--;
    ans=b-ans;
    //cout<<ans<<endl;
    ll ans1=(a/c+a/d-a/lcm);
    ans1=a-ans1;
    cout<<ans-ans1<<endl;
}