#include <bits/stdc++.h>
using namespace std;
const long double PI = acos(-1);
const long long MOD = 1000000007;
const long long FMOD = 998244353;
long long a[3005], b[3005], c[3005];
long long n;
long long dp[3005][2];
long long f(long long i, long long fl) {
  if (i == n - 1) {
    if (fl) return dp[i][fl] = b[i];
    return dp[i][fl] = a[i];
  }
  if (dp[i][fl] != -1) return dp[i][fl];
  long long ret = 0;
  if (fl) {
    ret = max(c[i] + f(i + 1, 0), b[i] + f(i + 1, 1));
  } else {
    ret = max(b[i] + f(i + 1, 0), a[i] + f(i + 1, 1));
  }
  return dp[i][fl] = ret;
}
void solve() {
  cin >> n;
  for (long long i = 0; i < n; i++) cin >> a[i];
  for (long long i = 0; i < n; i++) cin >> b[i];
  for (long long i = 0; i < n; i++) cin >> c[i];
  memset(dp, -1, sizeof dp);
  cout << f(0, 0);
}
signed main() { solve(); }
