#include<bits/stdc++.h>
#define ll long long 
using namespace std;

int main(){
  int t;
  cin >> t;
  while (t--){
    int n;
    cin >> n;
    ll a[2][n + 1], dp[2][n + 1];
    for (int i = 0; i < 2; i++){
      for (int j = 1; j <= n; j++){
        cin >> a[i][j];
        dp[i][j] = 0;
      }
    }
    dp[1][0] = -1e18;
    dp[0][1] = a[0][1];
    for (int i = 1; i < n; i++){
      if (i > 1) dp[0][i] = dp[0][i - 1] + max(a[0][i], 1LL * (-i));
      dp[1][i] = max(dp[0][i] + a[1][i], dp[1][i - 1] + max(a[1][i], 1LL * (-i)));
    }
    cout << max(dp[0][n - 1] + a[0][n], dp[1][n - 1]) + a[1][n] << endl;
  }
}