#include <bits/stdc++.h>
using namespace std;
int dp[3333][3], n, t1, t2;
int a[3333], b[3333], c[3333];
int fun(int pos, int f) {
  if (pos == n - 1) {
    if (f) return b[pos];
    return a[pos];
  }
  int& ret = dp[pos][f];
  if (ret != -1) return ret;
  ret = 0;
  if (f) {
    ret = b[pos] + fun(pos + 1, f);
    ret = max(ret, fun(pos + 1, 0) + c[pos]);
  } else {
    ret = a[pos] + fun(pos + 1, 1);
    ret = max(ret, fun(pos + 1, 0) + b[pos]);
  }
  return ret;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n;
  for (int i(0), _n(n); i < _n; ++i) cin >> a[i];
  for (int i(0), _n(n); i < _n; ++i) cin >> b[i];
  for (int i(0), _n(n); i < _n; ++i) cin >> c[i];
  memset(dp, -1, sizeof(dp));
  cout << fun(0, 0) << endl;
}
