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: Accepted)

#include <iostream>
#include <numeric>
#include <cmath>
#include <limits>
using namespace std;
typedef long long ll;
int main(){
  ll a,b,c,d,ans=0;cin>>a>>b>>c>>d;
    ll x=max(c,d),y=min(c,d);
  ll r=x%y;
  while(r!=0){
    x = y;
    y = r;
    r = x % y;
  }
  x=c*d/y;
  ans+=b/c;ans+=b/d;ans-=b/x;
  ans-=(a-1)/c;ans-=(a-1)/d;ans+=(a-1)/x;
  cout << b-a-ans+1<< endl;
}