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 hcf(long long int a,long long int b)
{
	if(b==0)
	{
		return a;
	}
	return hcf(b,a%b);
}
int main()
{
	long long int a,b,c,d,f,f1,s,s1,t1,t,k;
	scanf("%lld %lld %lld %lld",&a,&b,&c,&d);
	t=(b-a)+1;
	//printf("%lld\n",t);
	f=((b/c)-((a-1)/c));s=((b/d)-((a-1)/d));
	t1=(c*d)/hcf(c,d);
	k=(b/t1)-((a-1)/t1);
	//printf("%lld\n",f+s);
	/*if(c!=d)
	{
		printf("%lld\n",t);
	}
	else
		printf("%lld\n",t-(f+s)+k+1);*/
	t=t-(f+s)+k;
	printf("%lld\n",t);
	return 0;
}