#include <bits/stdc++.h>
using namespace std;
const long long int N = 3e3 + 5;
long long int a[N], b[N], c[N], dp[N][2], n;
long long int solve(long long int pos, long long int ch) {
  if (pos == n) {
    if (ch == 0)
      return a[pos];
    else
      return b[pos];
  }
  long long int &ans = dp[pos][ch];
  if (ans != -1) return ans;
  if (ch == 0) {
    long long int result1 = solve(pos + 1, 1) + a[pos];
    long long int result2 = solve(pos + 1, 0) + b[pos];
    return ans = max(result1, result2);
  } else {
    long long int result1 = solve(pos + 1, 1) + b[pos];
    long long int result2 = solve(pos + 1, 0) + c[pos];
    return ans = max(result1, result2);
  }
}
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  memset(dp, -1, sizeof(dp));
  cin >> n;
  for (long long int i = 1; i <= n; i++) cin >> a[i];
  for (long long int i = 1; i <= n; i++) cin >> b[i];
  for (long long int i = 1; i <= n; i++) cin >> c[i];
  cout << solve(1, 0);
  return 0;
}
