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: Time Limit Exceeded)

#include<bits/stdc++.h>

typedef long long ll;

using namespace std;

int main(){
    long long A, B, C, D;
    cin >> A >> B >> C >> D;
    long long sc = (A-1) / C + 1;
    long long sd = (A-1) / D + 1;
    long long count = 0;
    for(long long ll = sc*C ; ll <=B ; ll += C){
        if(ll % D != 0) count++;
    }
    for(long long ll = sd*D ; ll <=B ; ll += D){
        count++;
    }
    cout << B-A-count+1 << endl;
    return 0;
}