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<bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<string,ll>;
using Map = map<char,ll>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;

ll gcd(ll a,ll b) {
    while(1) {
    if(a < b) swap(a, b);
    if(!b) break;
    a %= b;
    }
    return a;
}
ll lcm(ll a, ll b){
    return a/gcd(a,b)*b;
}
ll F(ll x,ll C,ll D){
    return x-x/C-x/D+x/(lcm(C,D));
}

int main(){
    ll A;
    cin >> A;
    ll B;
    cin >> B;
    ll C;
    cin >> C;
    ll D;
    cin >> D;
    cout<<F(B,C,D)-F(A-1,C,D)<<endl;
return 0;
}