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
#define Mod 1000000007

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll a,b,c,d; cin>>a>>b>>c>>d;
    ll ans=b-a+1;
    ll l=(c*d)/__gcd(c,d);
    ll rem=(b/c + b/d - b/(l))-((a-1)/c + (a-1)/d - (a-1)/(l));
    cout<<ans-rem;
    return 0;
}