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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector")
#pragma GCC target("sse,sse2,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define watch(x) cout <<(#x)<<" is "<<(x)<<endl
#define debug cout <<"hi"<<endl
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
const int MOD=1e9+7;
const int INF32=1<<30;
const ll INF64=1LL<<60;

void solve(){
  ll a,b,c,d; cin >>a >>b >>c >>d;
  ll l=c*d/__gcd(c,d); a--;
  cout <<(b-a)-(b/c-a/c)-(b/d-a/d)+(b/l-a/l);
}

int main(){
  ios_base::sync_with_stdio(0); cin.tie(0);
  solve();
return 0;}