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>
#define int long long

main()
{
  int a,b,c,d;
  int count,r,tmp,x,y,z;
  
  scanf("%ld %ld %ld %ld",&a,&b,&c,&d);  
  
  x=c;
  y=d;
  z=x*y;
  
  if(x<y){
    tmp = x;
    x = y;
    y = tmp;
  }
 
  r = x % y;
  while(r!=0){
    x = y;
    y = r;
    r = x % y;
  }
  
  z=z/y;
  count=b-a+1;
  r=b/z-(a-1)/z;
  a=(a-1)/c+(a-1)/d;
  b=(b/c)+(b/d);
  
  count=count-(b-a-r);
  
  printf("%ld",count);
  
  return 0;
}