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 <iostream>
#include <vector>
#include <algorithm>
#include <cstdlib>
#include <math.h>
#include <unordered_map>
#include <numeric>
#include <sstream>
#include <functional>
using namespace std;

typedef long long int ll;

ll gcd(ll m, ll n){
	// 引数に０がある場合は０を返す
	if ( ( 0 == m ) || ( 0 == n ) )
		return 0;
	
	// ユークリッドの方法
	while( m != n )
	{
		if ( m > n ) m = m - n;
		else         n = n - m;
	}
	return m;
}//gcd


ll lcm(ll m, ll n){
	// 引数に０がある場合は０を返す
	if ( ( 0 == m ) || ( 0 == n ) )
		return 0;
	
	return ((m / gcd(m, n)) * n); // lcm = m * n / gcd(m,n)
}//lcm

int main()
{
	ll a,b,c,d,lcm_val,cnt_cd=0,cnt_lcm=0;

	cin >> a >> b >> c >> d;

	// (1)
	ll div_c = b/c - a/c;
	if(a%c == 0)
		div_c++;

	// (2)
	ll div_d = b/d - a/d;
	if(a%d == 0)
		div_d++;

	// (3)
	lcm_val = lcm(c,d);
	ll div_cd = b/lcm_val - a/lcm_val;

	// (4)
	ll all = div_c + div_d - div_cd;

	ll ans = (b-a+1)-all;

	cout << ans << endl;

	return 0;
}