Help Mocha - JAVA

package com.company;
import java.util.*;


public class Problem {

    private static final int N = 300000;

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int d = sc.nextInt();
        long result = helpMocha(d);
        System.out.println(result);
    }

    static boolean[] isPrime = new boolean[N+1];
    static ArrayList<Long> primes = new ArrayList<>();

    static void sieve(){
        for(long i=2; i <= N; i++){
            if(isPrime[(int)i]){
                for(long j = i*i; j <= N; j += i){
                    isPrime[(int)j] = false;
                }
                primes.add(i);
            }
        }
    }

    static long lowerBound(ArrayList<Long> list, long x){
        int n = list.size();
        int lo = 0, hi = n-1, res = n-1;

        while (lo <= hi){
            int mid = lo + (hi - lo)/2;
            if(list.get(mid) == x)
                return x;
            else if(list.get(mid) > x){
                res = mid;
                hi = mid-1;
            }else{
                lo = mid+1;
            }
        }

        return list.get(res);
    }


    static long helpMocha(int d){
        Arrays.fill(isPrime, true);
        sieve();

        long a = lowerBound(primes, 1 + d);
        long b = lowerBound(primes, a + d);

        return a*b;
    }

}