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>

int main(void)
{
	long int A, B, C, D, C2, D2;
	long int i;
	long int tmp, r, x,F, G;

	scanf("%ld", &A);
	scanf("%ld", &B);
	scanf("%ld", &C);
	scanf("%ld", &D);

  x = C * D;
 
  /* 自然数 a > b を確認・入替 */
  if(C<D){
    tmp = C;
    C = D;
    D = tmp;
  }
  C2 = C;
  D2 = D;	
 
  /* ユークリッドの互除法 */
  r = C % D;
  while(r!=0){
    C = D;
    D = r;
    r = C % D;
  }
  //printf("%ld", r);

  if(r == 0) r = 1;

	F = B - A;
	i = x /r;
	G = (F / C2) + (F / D2) - (F / i);
	//printf("%ld", F);
	//printf("%ld", G);

	printf("%ld", F-G);

	return 0;
}