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)

#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
#include <fstream>
#include<cstdio>
#include<iomanip>
#include<numeric>

#define REP(i, n) for(int i=0;i<n;i++)
#define REP2(i, s, n) for(int i=s;i<n;i++)
#define REP_1(i, n) for(int i=1;i<n+1;i++)
#define bitSearch(bit, n) for(int bit = 0; bit < (1 << N); bit++)
using namespace std;

void printAns(int a) { cout << a << endl; }

void yesno(bool a) { if (a)cout << "Yes" << endl; else cout << "No" << endl; }

void YESNO(bool a) { if (a)cout << "YES" << endl; else cout << "NO" << endl; }

typedef long long ll;
typedef unsigned long ul;
typedef long double ld;

template<class T>
inline bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
inline bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

ll INF = 10000000;
ll mod = 1000000007;//10^9+7


int multi(ll A,ll B, ll M){
    ll L=(A-1)/M+1;
    ll R=B/M;
    return R-L+1;
}

ll lcm(ll a, ll b){
    if(a<b){ll tmp=a;a=b;b=tmp;}
    ll x=a*b;
    ll r=a%b;
    while(r!=0){
        a=b;
        b=r;
        r=a%b;
    }
    return x/b;
}

//番号ズレ注意！！
int main() {
    ll A,B,C,D;
    cin>>A>>B>>C>>D;
    cout<<B-A+1-multi(A,B,C)-multi(A,B,D)+multi(A,B,lcm(C,D));
}