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,lcm,t;
    scanf("%lld %lld %lld %lld",&a,&b,&c,&d);
    int C=c;
    int D=d;
    while(C!=0&&D!=0){
        lcm=D;
        D=C%D;
        C=lcm;
    }
    lcm=c*d/lcm;
    t=b/c+b/d-b/lcm-(a-1)/c-(a-1)/d+(a-1)/lcm;
    printf("%lld\n",b-a+1-t);
    return 0;
}