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(long long a,long long b){
    if(a%b==0) return b;
    else return gcd(b,a%b);
}

int main(void){
    long long A,B,C,D;
    cin>>A>>B>>C>>D;
    long long num_c=B/C-(A-1)/C;
    long long num_d=B/D-(A-1)/D;
    long long com=C*D/gcd(C,D);
    long long num_com=B/com-(A-1)/com;
    long long ans=(B-A+1)-(num_c+num_d-num_com);
    cout<<ans<<endl;
    return 0;
}