#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  long long n;
  cin >> n;
  vector<long long> a(n), b(n), c(n);
  long long i;
  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];
  }
  long long prev_0[2][n], prev_1[2][n];
  prev_0[0][n - 1] = prev_1[0][n - 1] = 0;
  prev_0[1][n - 1] = a[n - 1];
  prev_1[1][n - 1] = b[n - 1];
  for (i = n - 2; i >= 0; i--) {
    prev_0[0][i] = prev_1[0][i] = max(prev_0[0][i + 1], prev_0[1][i + 1]);
    prev_0[1][i] = prev_1[1][i] = max(prev_1[0][i + 1], prev_1[1][i + 1]);
    prev_0[0][i] += b[i];
    prev_0[1][i] += a[i];
    prev_1[0][i] += c[i];
    prev_1[1][i] += b[i];
  }
  cout << max(prev_0[0][0], prev_0[1][0]) << "\n";
  return 0;
}
