#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cassert>

using namespace std;

const int MAXN = 100000 + 10;

int a[MAXN];
int b[MAXN];
int n;

int main(int argc, const char * argv[]) {
    int tn;
    cin >> tn;
    assert(1 <= tn && tn <= 10);
    while (tn--) {
        cin >> n;
        assert(1 <= n && n <= 10000);
        for(int i = 1; i <= n; i++) {
            cin >> a[i];
            assert(a[i] > a[i - 1]);
        }
        assert(a[n] < 1000000000);
        for(int i = 1; i <= n; i++) {
            cin >> b[i];
            assert(1 <= b[i] && b[i] <= 1000000000);
        }
        int ret = 0;
        for(int i = 1; i <= n; i++)
            if (a[i] - a[i - 1] >= b[i])
                ++ret;
        cout << ret << endl;
    }
    return 0;
}