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>
#include <stdlib.h>
#include <ctype.h>
#include <stdbool.h>

#define lli long long int
lli g(lli a, lli b)
{
	lli tmp;
	lli x = a*b;
	if (a<b)
	{
		tmp = a;
		a = b;
		b = tmp;
	}
	lli r = a%b;
	while (r!=0)
	{
		a = b;
		b = r;
		r = a%b;
	}
	return (x/b);
}

lli f(lli a, lli b, lli c)
{
	if (a == b)
	{
		if (a%c == 0)
			return (1);
		return (0);
	}

	lli small = a + (c - a%c)%c;
	lli big = (b/c)*c;
	if(small == big)
		return (1);
	return(1+((big - small)/c));
}
int main(void)
{
	lli a, b, c, d;
	scanf("%lld %lld %lld %lld",&a, &b, &c, &d);
	lli out = 0;
	lli by_c = f(a,b,c);
	lli by_d = f(a,b,d);
	//printf("debug:c:%lld\n",by_c);
	//printf("debug:d:%lld\n",by_d);

	lli e = g(c,d);
	//printf("debug:gcd:%lld\n",e);
	lli by_e = f(a,b,e);
	//printf("debug:e:%lld\n",by_e);

	out = b - a + 1;
	out = out - by_c - by_d + by_e;
	printf("%lld\n",out);
	return (0);
}