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==1) return 1;
    else if(a%b==0) return b;
    return gcd(b,a%b);
}

ll lcm(ll a,ll b){
    return (a*b)/gcd(a,b);
}

ll solve(ll a,ll b,ll c){
    return a/b + a/c - a/lcm(b,c);
}

int main(){
    ll A,B,C,D;
    scanf("%lld %lld %lld %lld",&A,&B,&C,&D);
    printf("%lld",B-A+1-(solve(B,C,D)-solve(A-1,C,D)));
}