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>
#define ll  long long
#define ff first
#define ss second
#define pb push_back
#define mp make_pair

using namespace std;
ll ma=1000000007;
ll power(ll p,ll t){
if(t==0)
    return 1;
ll y=power(p,t/2);
y=(y*y)%ma;
if(t%2==1)
    y=(y*p)%ma;
return y;
}


int mod(int a){
if(a>=0)
    return a;
else return -a;
}



 int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll a,b,c,d;
cin>>a>>b>>c>>d;
ll x=b-a+1;
ll y,z,p;
if(a%c==0){
    y=b/c-a/c+1;
}
else{
    y=b/c-a/c;
}
if(a%d==0){
    z=b/d-a/d+1;
}
else z=b/d-a/d;
ll f=(c*d)/__gcd(c,d);
if(a%f==0){

    p=b/f-a/f+1;
}
else p=b/f-a/f;


cout<<(x-(y+z-p))<<endl;


}