#include <bits/stdc++.h>
using namespace std;
vector<int> a, b, c;
int n;
int dp[2][3001];
void solve() {
  for (int idx = n - 1; idx >= 0; idx--) {
    if (idx + 1 == n) {
      dp[0][idx] = a[idx];
      dp[1][idx] = b[idx];
      continue;
    }
    dp[0][idx] = max(a[idx] + dp[1][idx + 1], b[idx] + dp[0][idx + 1]);
    dp[1][idx] = max(b[idx] + dp[1][idx + 1], c[idx] + dp[0][idx + 1]);
  }
}
int main() {
  cin >> n;
  a = b = c = vector<int>(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];
  }
  solve();
  cout << dp[0][0];
}
