JAVA AND PYTHON_B7 java practice problem 2

import java.util.Scanner;
import static java.lang.System.*;
import java.util.ArrayList;

public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(in);
    double n = scan.nextDouble();
    double sumX = 0;
    double sumW = 0;
    ArrayList<Double> ws = new ArrayList<Double>();
    for (double i = 0; i < n; ++i) {
      double w = scan.nextDouble();
      ws.add(w);
    }
    for (double i = 0; i < n; ++i) {
      double x = scan.nextDouble();
      sumX += x;
      sumW += ws.get((int)i) * x;
    }
    out.println(sumW / sumX);
  }
}