#include<bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define dbg(a,b,c,d) cerr<<a<<" "<<b<<" "<<c<<" "<<d<<endl;
#define kill(a) {cout<<a<<endl;continue;}
#define KILL(a) {cout<<a<<endl;return 0;}
#define debug cerr<<"Error Found"<<endl;
#define mem(a,b) memset(a,b,sizeof(a))
#define lcm(a, b) (a/__gcd(a,b))*b
#define w(t) cin>>t;while(t--)
#define pi 2 * acos(0.0)
#define endl "\n"
int t, cs = 0;
const int mxn = 2e5 + 3, mod = 1e9 + 7;
int vis[2][2][mxn], ar[2][mxn];
int64_t dp[2][2][mxn];
int m;
int64_t rec(int i, int j, bool k)
{
if(j == m)return -1e14;
if(i == 1 and j == m - 1)return ar[i][j];
if(vis[i][k][j] == cs)return dp[i][k][j];
vis[i][k][j] = cs;
int64_t ans = -1e15;
if(!k)
{
ans = ar[i][j] + max(rec(i, j + 1, 0), rec(i, j + 1, 1));
if(!i)ans = max(ans, ar[i][j] + rec(i + 1, j, k));
}
else ans = -j - 1 + max(rec(i, j + 1, 0), rec(i, j + 1, 1));
return dp[i][k][j] = ans;
}
int32_t main()
{
fast
w(t)
{
cin >> m;
for(int i = 0; i < 2; i++)for(int j = 0; j < m; j++)cin >> ar[i][j];
cs++;
cout << rec(0, 0, 0) << endl;
}
}