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 <bits/stdc++.h>
using namespace std;
#define rep(i,n) for( int i = 0 ; i < n ; i++ )
typedef long long ll;

ll gcd( ll a , ll b ) { return ( b ?  gcd(b,a%b) : a ) ; }
ll lcd( ll a , ll b ) { return ( a/gcd(a,b)*b ) ; }
ll f(ll x, ll c , ll d ){
  ll ans = x ;
  ans -= x/c ;
  ans -= x/d ;
  ans += x/lcd(c,d) ;
  return ans ;
}

int main() {
  ll a , b ;
  ll c , d ;
  cin >> a >> b ; 
  cin >> c >> d ;
  //cout << lcd(c,d) << endl ;
  cout << f(b,c,d) - f(a,c,d) << endl ;
}