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;

ll LCM(ll a, ll b) {
    ll t = a*b;
    return t/__gcd(a, b);
}

ll rangeDivisor(ll m, ll n, ll a, ll b) {
    ll lcm = LCM(a, b);
    ll a_divisor = n / a - (m - 1) / a;
    ll b_divisor = n / b - (m - 1) / b;
    ll common_divisor = n / lcm - (m - 1) / lcm;
    ll ans = a_divisor + b_divisor - common_divisor;
    return ans;
}

int main() {
    ll A, B, C, D;
    cin >> A >> B >> C >> D;

    ll ret = rangeDivisor(A, B, C, D);
    //cout << ret << endl;
    cout << B-A+1 - ret << endl;
    return 0;
}