// {In the Name of Allah, the Most Beneficent, the Most Merciful }
 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double dd;
#define mp make_pair
#define pb push_back
#define pf push_front
#define IOS ios_base::sync_with_stdio(0);cin.tie(NULL);
#define no cout<<"NO\n"
#define yes cout<<"YES\n"
#define el "\n"
 
 
int a[200005];
 
int main()
{
    /**/IOS/**/
    int t ;
    cin>>t;
    while(t--)
    {
    	int n , z=0 , b;
    	cin>>n;
    	
    	for(int i=0 ; i<n ; i++)
    		cin>>a[i];
		for(int i=0 ; i<n ; i++)
    	{
    		cin>>b;
    		if(a[i]<=b)
    		z=max(z,(b-a[i]));
    	}
    	
    	cout<<z<<el;
	}
     
     
     
}//main