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>
#include <math.h>
#include <cmath>
using namespace std;
using ll = long long;

ll yakusu(ll x, ll y, ll z){
  ll s = (x + z - 1) / z;
  ll t = y / z;
  ll u = t - s + 1;
  return u;
}

int main(){
  ll a, b; cin >> a >> b;
  ll c, d; cin >> c >> d;

  ll lc = (c * d) / __gcd(c, d);
  ll ans = yakusu(a, b, c) + yakusu(a, b, d) - yakusu(a, b, lc);
  cout << b - a + 1 - ans << endl;
}