KTTABLE

// https://www.codechef.com/problems/KTTABLE
#include <iostream>
using namespace std;

int main() {
    // your code goes here
       int t;
       cin>>t;
       while(t--){
            int n;
            cin>>n;
            int A[n+1];
            for(int i=1;i<=n;i++){
                cin>>A[i];
            }
            int B[n+1];
            for(int i=1;i<=n;i++){
                cin>>B[i];
            }
            int count=0;
            A[0]=0;
            for(int i=1;i<=n;i++){
                if(B[i]<=(A[i]-A[i-1])){
                    count++;
                }
            }
            cout<<count<<endl;
       }

    return 0;
}