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;
typedef long long ll;

ll f(ll i,ll a,ll b){
  ll count=0,k=1;
  while(k*i<a)
    k++;
  for(int j=a;j<=b;j++){
    if(j==k*i){
      k++;
      count++;
    }
  }
  return count;
}

int main(){
  ll a,b,c,d;
  cin >> a >> b >> c >> d;  
  cout << b-a+1-(f(c,a,b)+f(d,a,b)-f(c*d,a,b));
}