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: Wrong Answer)

#include <stdio.h>

long long gcd(long long a, long long b)
{
	if (a > b) {
		a += b;
		b = a - b;
		a -= b;
	}
	if (b % a == 0) return a;
	else return gcd(b % a, a);
}

int main()
{
	long long A, B, C, D;
	scanf("%lld %lld %lld %lld", &A, &B, &C, &D);
	
	long long G = gcd(C, D), L = (C / G) * D;
	int c = B / C - (A - 1) / C, d = B / D - (A - 1) / D, l = B / L - (A - 1) / L;
	printf("%lld\n", (B - A + 1) - c - d + l);
	fflush(stdout);
	return 0;
}