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: Wrong Answer)

// Gaurav Aggarwal
 
/*
useful stl
array<ll,size> ar;         //size(),front(),back(),fill(),empty()
deque<ll> d                //push_back(),push_front(),pop_front(),pop_back()
vector<ll> v(size,val);    //push_back(),*max_element(v.begin(),v.end()),accumulate(v.begin(),v.end(),0)
stack<ll> g;               //push(),pop(),top(),size(),empty()         LIFO
queue<ll> q;               //push(),size(),front(),back(),empty()      FIFO
priority_queue<ll> pq
*/
 
#include<bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<pii > vii;
typedef vector<pll > vll;
#define pb push_back
#define mp make_pair 
#define mod 1000000007
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define For(i, a, b) for(__typeof (a) i=a; i<=b; i++)
#define inp_arr(a,n) for(__typeof (n) i=0; i<n; ++i) {cin>>a[i];}
#define debug_arr(a,n) {{for(__typeof (n) i=0; i<n; ++i) {cout<<a[i]<<" ";}cout<<"\n";}}

ll power(ll x, ll y) 
{ 
    ll res = 1;   
    while (y > 0) { 
        if (y & 1) 
            res = (res*x)%mod; 
        y = y>>1;
        x = (x*x)%mod; 
    } 
    return res%mod; 
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
 
    // #ifndef ONLINE_JUDGE
    // freopen("input.txt", "r", stdin);
    // freopen("out.txt", "w", stdout); 
    // #endif  

    ll a,b,c,d;

    cin>>a>>b>>c>>d;

    int numc = b/c - (a-1)/c;
    int numd = b/d - (a-1)/d;

    ll gc = __gcd(c,d);
    ll lc = (c*d)/gc;
    // cout<<(c*d)/gc<<"\n";

    int f = b/lc - (a-1)/lc;

    ll ans = (b - a + 1) + f - numc - numd;
    cout<<ans<<"\n"; 

    return 0;
}