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;
#define ll long long
#define ull unsigned long long

int main()
{
    ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t=1;
//cin>>t;
while(t--){
ull int a,b,c,d;
cin>>a>>b>>c>>d;
ull int start1;
if(a%c==0){
    start1=a/c;
}
else{start1=(a/c)+1;}
ull int start2;
if(a%d==0){start2=a/d;}
else{start2=(a/d)+1;}
ull int start3;
ull int kya=(c*d)/__gcd(c,d);
if(a%kya==0){
    start3=a/kya;
}
else{start3=(a/kya)+1;}
cout<<b-a+1-((b/c)-start1+1)-((b/d)-start2+1)+((b/kya)-start3+1)<<endl;
}}