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: Accepted)

#include<stdio.h>
long long int gcd(long long int a, long long int b)
{
	long long int r = a % b;
	while (r > 0)
	{
		a = b;
		b = r;
		r = a % b;
	}
	return b;
}
int main()
{
	long long int a, b, c, d;
	scanf("%lld %lld %lld %lld", &a, &b, &c, &d);
	a--;
	long long int ans = b - a;
	ans -= b / d;
	ans -= b / c;
	ans += a / c;
	ans += a / d;
	long long int g = c * d / gcd(c, d);
	ans += b / g;
	ans -= a / g;
	printf("%lld\n", ans);
	return 0;
}