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){
	if(a<b){
		long long int t;
		t=a;
		a=b;
		b=t;
	}
	long long int r;
	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);
	long long int ans;
	ans=B-A+1;
	ans=ans-B/C+(A-1)/C;
	ans=ans-B/D+(A-1)/D;
	long long int E;
	E=C*D/gcd(C,D);
	ans=ans+B/E-(A-1)/E;
	printf("%lld",ans);
}