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>
#include<cmath>
using namespace std;

int main()
{
  long long int A, B;
  int C, D;
  cin >> A >> B >> C >> D;
  long long int count =  B - A + 1;
  int C_d = (B / C) - ((A-1) / C);
  int D_d = (B / D) - ((A-1) / D);
  long long CD = (long long)C * D;
  int r;
  while(D % C != 0) {
    r = C;
    C = D % C;
    D = r;
  }
  int C_D_d = (B / (long long)(CD / C)) - ((A - 1)/ (long long)(CD / C));
  cout << count - C_d - D_d + C_D_d << endl;
  return 0;
}