#include <bits/stdc++.h>
using namespace std;
int n;
int a[3200];
int b[3200];
int c[3200];
int d[3200];
int e[3200];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  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];
  d[1] = a[1];
  e[1] = b[1];
  for (int i = 2; i <= n; i++) {
    d[i] = max(a[i] + e[i - 1], b[i] + d[i - 1]);
    e[i] = max(b[i] + e[i - 1], c[i] + d[i - 1]);
  }
  cout << d[n] << endl;
  return 0;
}
