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>

int main(){
    long long int a,b,c,d,tmp,r,mina,minb;
    long long int x,y,z,C,D;
    

    scanf("%lld %lld %lld %lld",&a,&b,&C,&D);

    mina = (a-1)/C;
    minb = b/C;
    y = minb-mina;
    mina = (a-1)/D;
    minb = b/D;
    z = minb-mina;

    
  /* ユークリッドの互除法 */
     c = C;
     d = D;
     x = c*d;
    
     if(c < d){
    	tmp = c;
    	c = d;
    	d = tmp;
	}
    r = c%d;
    while(r!=0){
    	c = d;
    	d = r;
    	r = c % d;
  	}
    x = x/d;
    mina = (a-1)/x;     
    minb = b/x;
    x = minb-mina;

   

    printf("%lld\n",b-a+1-(y+z-x));
    return 0;

}