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>
#include <string>
#define INF 100000
using namespace std;
int H, W,N;
int sx, sy;
typedef long long ll;

int main(){
    ll a,b,c,d;
    cin >> a >> b >> c >> d;
    ll cans,dans,cdans,cd;
    cans = b/c - a/c + (a%c==0);
    dans = b/d - a/d + (a%d==0);
    ll mx= max(c,d);
    ll mn= min(c,d);
    ll amali = 1;
    ll koyaku;
    while(amali){
        amali = mx%mn;
        if(amali ==0) koyaku = mn;
        mx = mn;
        mn = amali;

    }


     cd = c*d/koyaku;
    cdans = b/cd - a/cd +(a%cd==0);
    ll ans;
    ans = 1+b-a-cans-dans+cdans;
     cout << ans << endl;
    // cout << cans << endl;
    // cout << dans << endl;
    // cout << cdans << endl;

    return 0;
}