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: Wrong Answer)

#include <stdio.h>
#include <algorithm>
#include <iostream>
using namespace std;
long long gcd(long long a, long long b)
{
    long long r=0, t=0;

    while(b!=0){
        r=a%b;
        a=b;
        b=r;
    }

    return a;
}
long int lcm(long int a, long int b)
{
    return a/gcd(a, b)*b;
}
int main(void)
{
    long int a, b, c, d, ans;
    double bc, ac, bd, ad, acd, bcd;
    cin >> a >> b >> c >> d;

    bc=b/c;
    ac=(a-1)/c;
    bd=b/d;
    ad=(a-1)/d;
    acd=(a-1)/lcm(c, d);
    bcd=b/lcm(c,d);
    ans=b-a-(bc-ac+bd-ad-(bcd-acd))+1;
    cout << ans <<endl;
        
    return 0;
}