#include <bits/stdc++.h>
using namespace std;
int a[3003];
int b[3003];
int c[3003];
int dp[4000][3];
int f(int i, int trn) {
  if (i == 0) {
    if (trn == 0) {
      return b[i];
    } else {
      return a[i];
    }
  }
  if (dp[i][trn] != -1) {
    return dp[i][trn];
  }
  if (trn == 0) {
    int t = max(b[i] + f(i - 1, 0), c[i] + f(i - 1, 1));
    return dp[i][trn] = t;
  } else {
    int t = max(a[i] + f(i - 1, 0), b[i] + f(i - 1, 1));
    return dp[i][trn] = t;
  }
}
int main() {
  int n;
  memset(dp, -1, sizeof(dp));
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < n; i++) {
    cin >> b[i];
  }
  for (int i = 0; i < n; i++) {
    cin >> c[i];
  }
  cout << f(n - 1, 1) << "\n";
}
