#include <iostream>
using namespace std;
 
int a[11111], b[11111];
 
int main() {
	int t;
	cin >> t;
	while (t --> 0) {
		int n;
		cin >> n;
		for(int i = 0; i < n; ++i)
			cin >> a[i];
		for(int i = 0; i < n; ++i)
			cin >> b[i];
		int ans = 0, last = 0;
		for(int i = 0; i < n; ++i) {
			if (a[i] >= last + b[i])
				ans++;
			last = a[i];
		}
		cout << ans << "\n";
	}
	return 0;
}