import java.math.BigInteger;
import java.util.Scanner;

public class B390 {
    public static void main(String[] args) {
        BigInteger happiness = BigInteger.valueOf(0);
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] a = new int[n];
        int[] b = new int[n];
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < n; j++) {
                if (i == 0) {
                    a[j] = sc.nextInt();
                } else {
                    b[j] = sc.nextInt();
                }
            }
        }
        BigInteger x;
        BigInteger y;
        for (int i = 0; i < n; i++) {
            if (b[i] == 1) {
                happiness = happiness.subtract(BigInteger.valueOf(1));
            }
            if (a[i] * 2 < b[i]) {
                happiness = happiness.subtract(BigInteger.valueOf(1));
            } else {
                if (b[i] % 2 == 0) {
                    x = BigInteger.valueOf(b[i] / 2);
                    happiness = happiness.add(x.multiply(x));
                } else {
                    x = BigInteger.valueOf((b[i] - 1) / 2);
                    y = BigInteger.valueOf((b[i] + 1) / 2);
                    happiness = happiness.add(x.multiply(y));
                }
            }
        }
        System.out.println(happiness);
    }
}