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>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <time.h>

long long fgcm(long long a,long long b){
	long long ab;
	
	while(b!=0){
		a=a%b;
		ab=a; a=b; b=ab;
	}
	
	return a;
}

int main(void){
	long long na,nb,ans,gcm,lcm;
	
	long long a,b;
	
	long long c,d;
	
	scanf("%lld%lld%lld%lld",&a,&b,&c,&d);
	
	if(c>=d){
		gcm=fgcm(c,d);
	}else{
		gcm=fgcm(d,c);
	}
	
	a--;
	
	lcm=c*d/gcm;
	
	nb=b-floor(b/c)-floor(b/d)+floor(b/lcm);
	na=a-floor(a/c)-floor(a/d)+floor(a/lcm);
	
	printf("%lld\n",nb-na);
	
	return 0;
}