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 gcd(long a, long b){
	//if(a < b)return gcd(b, a);
	if(a % b == 0){
		return b;
	}else{
		return gcd(b, a % b);
	}
}

int main(void){
	long a, b, c, d;
	scanf("%ld %ld %ld %ld", &a, &b, &c, &d);
	a--;
	long sum = b - a;
	sum -= b / c - a / c;
	sum -= b / d - a / d;
	long tmp = c * d / gcd(c, d);
	sum += b / tmp - a / tmp;
	printf("%ld\n", sum);
	return 0;
}