#include <bits/stdc++.h>
using namespace std;
int n, a[3005], b[3005], c[3005], dp1[3005], dp2[3005];
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  for (int i = 1; i <= n; i++) {
    cin >> b[i];
  }
  for (int i = 1; i <= n; i++) {
    cin >> c[i];
  }
  dp1[n] = a[n];
  dp2[n] = b[n];
  for (int i = n - 1; i >= 1; i--) {
    dp1[i] = max(a[i] + dp2[i + 1], b[i] + dp1[i + 1]);
    dp2[i] = max(b[i] + dp2[i + 1], c[i] + dp1[i + 1]);
  }
  cout << dp1[1] << endl;
}
