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 int gcd(long int a,long int b){
    long int r,tmp;
    r = a % b;
    while(r != 0){
        a = b;
        b = r;
        r = a % b;
    }
    return b;
}



int main(void){
    long int a,b,c,d,lcm,ans;

    scanf("%ld%ld%ld%ld",&a,&b,&c,&d);

    lcm = c * d / gcd(c,d);

    ans = b - b/c - b/d + b/lcm - ( (a-1) - (a-1)/c -(a-1)/d +(a-1)/lcm );

    printf("%ld",ans);

    return 0;
}