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 <bits/stdc++.h>
#include <sstream>

using namespace std;

int cntn(long n,long a,long b){
  return b/n - (a-1)/n;
}

int main() {
  long a,b,c,d;
  cin >> a>>b>>c>>d;
  long ans=0;

  long prod = c*d;
  
  long u = b-a+1;

  ans = u - cntn(c,a,b) -cntn(d,a,b);
    
  long r = d % c;
  while(r!=0){
    d = c;
    c = r;
    r = d % c;
  }

  
  ans += cntn(prod/c,a,b);
  cout<<ans<<endl;
}