Complex Multiplication - JAVA

package com.company;

import java.util.ArrayList;
import java.util.Scanner;

public class Problem {

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        ArrayList<Long> real = new ArrayList<>();
        ArrayList<Long> imaginary = new ArrayList<>();

        for(int i=0; i<n; i++){
            long num = sc.nextLong();
            real.add(num);
        }

        for(int i=0; i<n; i++){
            long num = sc.nextLong();
            imaginary.add(num);
        }


        ArrayList<Long> result = multiplyComplexNumbers(real, imaginary, n);
        System.out.println(result.get(0) + " + (" + result.get(1) + ")i");
    }

    public static ArrayList<Long> multiplyComplexNumbers(ArrayList<Long> real, ArrayList<Long> imaginary,  int n){
        ArrayList<Long> result = new ArrayList<>();
        result.add(1L);
        result.add(0L);

        for(int i=0; i < n; i++){
            result = multiply(result.get(0), result.get(1), real.get(i), imaginary.get(i));
        }
        return result;
    }

    public static ArrayList<Long> multiply(long a, long b, long x, long y){
        // ax - by + i(bx + ay)
        long MOD = 1000000007;
        ArrayList<Long> result = new ArrayList<>();
        result.add((a*x - b*y)%MOD);
        result.add((b*x + a*y)%MOD);
        return result;
    }

}