#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < b; i++)
using ll = long long;

int main(){
	int n;;
	cin >> n;
	vector<int> t(n), s(n);;
	rep(i, 0, n) cin >> t[i];
	rep(i, 0, n) cin >> s[i];
	int ans = 0;
	double now = 0;
	rep(i, 0, n) {
		if(now < s[i]) {
			now = s[i] + t[i] - 0.1;
			ans++;  
		}
	}
	cout << ans << endl;
}