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;
long long gcd(int x,int y);
long long lcm(int x,int y);
int main(){
    long long a,b;
    int c,d;
    cin>>a>>b>>c>>d;
    long long divc=b/c;
    long long divd=b/d;
    //cout<<lcm(c,d)<<endl;
    cout<<(b-(divc+divd-b/lcm(c,d)))-((a-1)-((a-1)/c+(a-1)/d-(a-1)/lcm(c,d)))<<endl;
    return 0;
}
long long gcd(int x,int y){
    if(y==0)return x;
    else return gcd(y,x%y);
}
long long lcm(int x,int y){
    return x/gcd(x,y)*y;
}