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: Wrong Answer)


#include <stdio.h>
long long lcm(int a,int b){
    if(b>a){
        int tmp=b;
        b=a;
        a=tmp;
    }
    long long inia=a,inib=b;
    int r=a%b;
    while(r>0){
        a=b;
        b=r;
        r=a%b;
    }
    return inia*inib/b;
}
int main()
{   int c,d;
    long long a,b;
    scanf("%lld%lld",&a,&b);
    scanf("%d%d",&c,&d);
    long long range=b-a;
    long long co=lcm(c,d);
    long long ans=0;
    ans+=(range/c);
    if(range%c>0&&(a+range/c+1)*c<=b){
        ans++;
    }
    ans+=(range/d);
    if(range%d>0&&(a+range/d+1)*d<=b){
        ans++;
    }
    ans-=(range/co);
    if(range%co>0&&(a+range/co+1)*co<=b){
        ans--;
    }
    printf("%lld",range-ans);
    return 0;
}