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>
using namespace std;


int gcd(long long a, long long b) {
  if(a < b) return gcd(b, a);
  long long r;
  while ((r=a%b)) {
    a = b;
    b = r;
  }
  return b;
}
int main(){
  long long A,B,C,D;
  cin >>A>>B>>C>>D;
  long long E=C*D/gcd(C,D);
  //cout<<B-A+1<<" "<<B/C-A/C<<" "<<B/D-A/D<<" "<< B/E-A/E<<endl;
  cout<<B-A+1-(B/C-A/C)-(B/D-A/D)+(B/E-A/E)<<endl;
  return 0;
}