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 (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>

typedef long long ll;

ll gcd(ll a, ll b){
    if(b == 0){
        return a;
    }else{
        return gcd(b, a%b);
    }
}

int main(void){
    ll A, B, C, D;
    ll cnt;
    ll i;
    ll g;
    ll Ac, Ad, Bc, Bd, Al, Bl;

    scanf("%lld %lld %lld %lld", &A, &B, &C, &D);

    g = gcd(C, D);
    ll lcm = C*D/g;

    Ac = A/C;
    Ad = A/D;
    Bc = B/C;
    Bd = B/D;
    Al = A/lcm;
    Bl = B/lcm;

    cnt = (Bc - Ac) + (Bd - Ad) -(Bl - Al);

    if(A%C == 0){
        cnt++;
    }
    if(A%D == 0){
        cnt++;
    }
    if(A%lcm == 0){
        cnt--;
    }

    cnt = (B-A+1)-cnt;

    printf("%lld", cnt);
    return 0;
}