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>
using namespace std;
#define lli long long int
//#include<boost\multiprecision\cpp_int.hpp>
//using namespace boost::multiprecision;
lli gcd(lli a,lli b){
  if(a==0)
    return b;
  if(b>a)
    return gcd(b,a);
  return gcd(a%b,b);
}
int main(){
  lli a,b,c,d,sum1=0,sum2=0,sum3=0,i,k;
  cin>>a>>b>>c>>d;
  if((c%d==c)||(d%c==d))
    k=1;
  else
    k=(c*d)/gcd(c,d);
  //cout<<k<<"\n";
  if(b%c==0)
    sum1++;
  sum1=sum1+(b-a)/c;
  if(b%d==0)
    sum2++;
  sum2=sum2+(b-a)/d;
  if(b%(k)==0)
    sum3++;
  sum3=sum3+(b-a)/(k);
  cout<<(b-a+1)-(sum1+sum2-sum3);
  return 0;
}