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 <iostream>
#define rop(i,n) for(int i = 0; i < (n); i++)
typedef long long ll;
using namespace std;

ll gcd(ll c, ll d)
{
    return d ? gcd(d, c%d) : c;
}

ll lcm(ll c, ll d)
{
    return c/gcd(c,d)*d;
}

ll f(ll n,ll c,ll d)
{
    int as = n;
    as -= n / c;
    as -= n / d;
    as -= n / lcm(c, d);
    return as;
}

int main()
{
    ll a, b, c, d;
    ll ans;
    cin >> a >> b >> c >> d;

    ans = f(b,c,d) - f(a-1,c,d);

    cout << ans << endl;

    return 0;
}