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<math.h>
#include <algorithm>
#include<float.h>
#include <limits>
#include <numeric>
using namespace::std;
int main(){

 long long int A;
 long long int B;
 long long int C;
 long long int D;
  cin>>A>>B>>C>>D;
 long long int tmp;
 long long int tc=C;
 long long int td=D;
  

  
  if(tc<td){
    tmp=td;
    td=tc;
    tc=tmp;
  }
  
  tmp=tc%td;
  while(tmp!=0){
    tc=td;
    td=tmp;
    tmp=tc%td;
  }
  if(A==B){
    cout<<((A%C)&&(A%D));
  }else{
  long long int L=C*D/td;
    
   long long int BC = B/C;
   long long int BD = B/D;
    long long int BL = B/L;
    long long int AC = (A-1)/C;
    long long int AD = (A-1)/D;
    long long int AL = (A-1)/L;
 
  cout<<B-A+1-(BC-AC)-(BD-AD)+(BL-AL);
  }
}