#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, k, l, n, test_case, m, r;
  test_case = 1;
  while (test_case--) {
    cin >> n;
    vector<vector<int> > vec(3, vector<int>(n));
    vector<vector<int> > dp(n, vector<int>(4));
    for (i = 0; i < n; i++) cin >> vec[0][i];
    for (i = 0; i < n; i++) cin >> vec[1][i];
    for (i = 0; i < n; i++) cin >> vec[2][i];
    dp[0][0] = vec[0][0];
    dp[0][2] = vec[1][0];
    for (i = 1; i < n; i++) {
      dp[i][0] = vec[0][i] + max(dp[i - 1][3], dp[i - 1][2]);
      dp[i][1] = vec[1][i] + max(dp[i - 1][0], dp[i - 1][1]);
      dp[i][2] = vec[1][i] + max(dp[i - 1][3], dp[i - 1][2]);
      dp[i][3] = vec[2][i] + max(dp[i - 1][0], dp[i - 1][1]);
    }
    cout << max(dp[n - 1][0], dp[n - 1][1]) << "\n";
  }
  return 0;
}
