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;
typedef long long LL;

bool IsPrime(int num){
    if (num < 2) return false;
    else if (num == 2) return true;
    else if (num % 2 == 0) return false;
    double sqrtNum = sqrt(num);
    for (int i = 3; i <= sqrtNum; i += 2){
        if (num % i == 0)
        {
            return false;
        }
    }
    return true;
}
LL gcd(LL m, LL n){
    LL temp;
    while(n!=0){
    temp=n;
    n=m%n;
    m=temp;
  }
  return m;
}
LL lcm(LL m,LL n){
  return m*n/gcd(m,n);
}
int main(){
  LL A,B;
  LL C,D;
  cin>>A>>B>>C>>D;
  A--;
  A-=(A/C)+(A/D)-A/lcm(C,D);
  B-=(B/C)+(B/D)-B/lcm(C,D);
  cout<<B-A<<endl;
  return 0;
}