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 long int gcd(long long int a,long long int b);

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

    scanf("%lld %lld %lld %lld",&a,&b,&c,&d);
    e = c * d / gcd(c,d);
    //printf("%lld %lld %lld %lld %lld",a,b,c,d,e);
    ans = (b - (a - 1)) - ((b / c) - ((a - 1) / c)) - ((b / d) - ((a - 1) / d)) + ((b / e) - ((a - 1) / e));

    printf("%lld",ans);
}

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