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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <sstream>
#include <vector>
#include <cmath>
#include <cstdio>
#include <queue>
#include <set>
#include <map>
#include <cstdlib>
#include <cstring>
#include <algorithm>
using namespace std;
long long gcd(long long a,long long b)
{

return b==0?a:gcd(b,a%b);
}

int main()
{
long long a,b,c,d;
scanf("%lld%lld%lld%lld",&a,&b,&c,&d);
long long t,tt,kk,k,sum;
long long ans=0;
t=a/c;
tt=b/c;
k=a/d;
kk=b/d;
t=tt-t;
k=kk-k;
if(c>d)
sum=gcd(c,d);
else
sum=gcd(d,c);
tt=c/sum;
kk=d/sum;
tt=tt*kk*sum;
kk=b/tt;
tt=a/tt;
tt=kk-tt;
ans=b-a-t-k+tt+1;
if(a%c==0&&a%d!=0||a%c!=0&&a%d==0)
ans--;

printf("%lld\n",ans);
}