#include <iostream>
#include <vector>

int main() {
	int n;
	std::cin >> n;
	std::vector<int> t(n);
	std::vector<int> s(n);
	
	for (auto& e : t) {
		std::cin >> e;
	}
	
	for (auto& e : s) {
		std::cin >> e;
	}
	
	int ans{};
	double finish = 0.0;
	
	for (int i = 0; i < n; ++i) {
		if (finish < s[i]) {
			++ans;
			finish = s[i] + t[i] - 0.1;
		}
	}

    std::cout << ans << std::endl;
}