#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<int> a, b, c;
  a.push_back(0);
  b.push_back(0);
  c.push_back(0);
  for (int i = 0; i < n; i++) {
    int temp;
    cin >> temp;
    a.push_back(temp);
  }
  for (int i = 0; i < n; i++) {
    int temp;
    cin >> temp;
    b.push_back(temp);
  }
  for (int i = 0; i < n; i++) {
    int temp;
    cin >> temp;
    c.push_back(temp);
  }
  if (n == 1) {
    cout << a[1];
    return 0;
  }
  int dp[n + 1][2];
  dp[n][0] = a[n];
  dp[n][1] = b[n];
  for (int i = n - 1; i > 0; i--) {
    dp[i][0] = max(a[i] + dp[i + 1][1], b[i] + dp[i + 1][0]);
    dp[i][1] = max(b[i] + dp[i + 1][1], c[i] + dp[i + 1][0]);
  }
  cout << max(b[1] + dp[2][0], a[1] + dp[2][1]);
  return 0;
}
