#include <bits/stdc++.h>
using namespace std;
const int N = 3001;
int n, dp[N][2], a[N], b[N], c[N];
int solve(int i, int j) {
  if (i == n - 1) {
    if (j) return b[i];
    return a[i];
  }
  if (dp[i][j] != -1) return dp[i][j];
  int res = 0;
  if (j) {
    res = max(res, b[i] + solve(i + 1, 1));
    res = max(res, c[i] + solve(i + 1, 0));
  } else {
    res = max(res, a[i] + solve(i + 1, 1));
    res = max(res, b[i] + solve(i + 1, 0));
  }
  return dp[i][j] = res;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (int i = 0, ggdem = n; i < ggdem; i++) cin >> a[i];
  for (int i = 0, ggdem = n; i < ggdem; i++) cin >> b[i];
  for (int i = 0, ggdem = n; i < ggdem; i++) cin >> c[i];
  memset(dp, -1, sizeof(dp));
  cout << solve(0, 0) << endl;
}
