#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const double PI = acos(-1.0);
const int N = 3003;
int n;
int a[3][N];
int dp[N][2];
int go(int at, int val) {
  if (at == n - 1) {
    return a[val][at];
  }
  int &r = dp[at][val];
  if (r != -1) return r;
  int L, R;
  L = R = 0;
  L = go(at + 1, 1) + a[val][at];
  R = go(at + 1, 0) + a[val + 1][at];
  return r = max(L, R);
}
int main(void) {
  ios_base::sync_with_stdio(false);
  cin >> n;
  for (int i = 0; i < 3; i++)
    for (int j = 0; j < n; j++) cin >> a[i][j];
  a[2][n - 1] = a[1][n - 1];
  memset(dp, -1, sizeof dp);
  cout << go(0, 0) << endl;
  return 0;
}
