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 gcd(long int m, long int n){
    long int temp;
    while (m % n != 0){
        temp = n;
        n = m % n;
        m = temp;
    }
    return n;
}

int main(void){
    long int a,b,c,d;
    scanf("%ld %ld %ld %ld", &a, &b, &c, &d);
    long int e,f,g,h,l,tmp;
    e = b/c;
    f = b/d;
    tmp = gcd(c,d);
    tmp = c*d/tmp;
    g = b/tmp;
    h = e+f-g;
    h = b-h;

    a--;
    e = a/c;
    f = a/d;
    g = a/tmp;
    l = e+f-g;
    l = a-l;

    long int ans = h-l;

    printf("%ld", ans);

    return 0;
}