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;

long long get(long long num, long long d)
{
      return num / d;
}

int main()
{
      long long A, B, C, D;
      cin >> A >> B >> C >> D;
      long long lcm = C / __gcd(C, D) * D;
      long long ans = get(B, C) - get(A-1, C) + get(B, D) - get(A-1, D) - get(B, lcm) + get(A-1, lcm);
      ans = B - A + 1 - ans;
      cout << ans << endl;
}