#include <bits/stdc++.h>
using namespace std;
int a[3005];
int b[3005];
int c[3005];
int dp[2][3005];
int n;
int solve(int last, int index) {
  if (index == n - 1) {
    return last == 0 ? a[index] : b[index];
  }
  if (dp[last][index] != -1) {
    return dp[last][index];
  }
  int ans = 0;
  if (last == 0) {
    ans = max(ans, a[index] + solve(1, index + 1));
    ans = max(ans, b[index] + solve(0, index + 1));
  } else {
    ans = max(ans, b[index] + solve(1, index + 1));
    ans = max(ans, c[index] + solve(0, index + 1));
  }
  dp[last][index] = ans;
  return ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  int i, j, k, t, x, y, q;
  cin >> n;
  memset(dp, -1, sizeof(dp));
  for (i = 0; i < n; i++) cin >> a[i];
  for (i = 0; i < n; i++) cin >> b[i];
  for (i = 0; i < n; i++) cin >> c[i];
  cout << solve(0, 0);
  return 0;
}
