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++ (GCC 5.4.1) (judge verdict: Time Limit Exceeded)

#include <bits/stdc++.h>
#define REP(i, a, b) for (long long i = a; i <= b; ++i)
#define ll long long
using namespace std;

ll a, b, c, d, ans;

inline ll read(){
	ll s = 0, w = 1;
	char ch = getchar();
	while (ch < '0' || ch > '9'){
		if (ch == '-') w *= -1;
		ch = getchar();
	}
	while (ch >= '0' && ch <= '9'){
		s = s * 10 + ch - '0';
		ch = getchar();
	}
	return s * w;
}

inline void work(){
	a = read(), b = read(), c = read(), d = read();
	REP(i, a, b)
		if (i % c > 0 && i % d > 0) ans++;
	printf("%lld\n", ans);
}

int main(){
	work();
	return 0;
}