import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] t = new int[n];
		for (int i = 0; i < n; i++) {
			t[i] = sc.nextInt();
		}
		int[] s = new int[n];
		for (int i = 0; i < n; i++) {
			s[i] = sc.nextInt();
		}
		sc.close();

		int ans = 0;
		int end = 0;
		for (int i = 0; i < n; i++) {
			if (end <= s[i]) {
				ans++;
				end = s[i] + t[i];
			}
		}
		System.out.println(ans);
	}
}