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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#define PI 3.1415926535897932
#define _GLIBCXX_DEBUG
#define MOD 1000000007;
using namespace std;
long long GCD(long long A,long long B){
  if(B==0){
    return A;
  }
  else{
    return GCD(B,A%B);
  }
}
int main() {
  
  long long A,B,C,D;
  cin>>A>>B>>C>>D;
  
  long long all=B-A+1;
  
  long long sum_C=B/C-(A-1)/C;
  
  long long sum_D=B/D-(A-1)/D;
  
  long long x=C*D/GCD(C,D);
  
  long long sum_CD=B/x-(A-1)/x;
  
  cout<<all-sum_C-sum_D+sum_CD<<endl;
}