#include <bits/stdc++.h>
using namespace std;
const int N = 3100;
int a[N], b[N], c[N], n;
int d[N][2];
int calc(int pos, int s) {
  if (pos == n) {
    if (s) return b[pos];
    return a[pos];
  }
  if (d[pos][s] != -1) return d[pos][s];
  if (s) {
    d[pos][s] = max(calc(pos + 1, 0) + c[pos], calc(pos + 1, 1) + b[pos]);
  } else {
    d[pos][s] = max(calc(pos + 1, 0) + b[pos], calc(pos + 1, 1) + a[pos]);
  }
  return d[pos][s];
}
int main() {
  freopen("input.txt", "r", stdin);
  ios::sync_with_stdio(0);
  for (int i = 0; i < N; i++) d[i][0] = d[i][1] = -1;
  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];
  }
  cout << calc(1, 0) << endl;
  return 0;
}
