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;
typedef long long ll ;
long const M=1000000007;
ll po(ll x, ll y) {
    ll t; 
    if( y == 0) 
        return 1; 
    t = po(x, y/2); 
    if (y%2 == 0) 
        return t*t; 
    else
        return x*t*t; 
} 

int main() {
    ll a , b ,c,d,numc,numl,numd ;
    cin >> a >>b >> c >>d;
    ll l = (c*d)/__gcd(c,d) ;
    if(a % c ==0)
        numc = b/c-a/c+1 ;
    else
        numc = b/c-a/c ;
    if(a%d ==0)
        numd = b/d-a/d+1 ;
    else
        numd = b/d-a/d ;
    if(a%l==0)
        numl = b/l-a/l +1;
    else
        numl = b/l-a/l ;
    cout << b-a + 1-(numc+numd-numl )<< endl ;
    
    return 0;
}