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: Wrong Answer)

#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0;i < (n);i++)
using namespace std;
using ll = long long;

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

int lcm (int a,int b){
  	return a * b /gcd(a,b);
}

int main(){
    ll a,b,c,d;
    cin >> a >> b >> c >> d;
    ll s = lcm(c,d);
    ll x = b/c + b/d - b/s;
    ll y = (a-1)/c + (a-1)/d +(a-1)/s;
    cout << b-(a-1)-(x-y) << endl;
}