#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  int n, a[3001], b[3001], c[3001];
  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];
  int dp[3001];
  memset(dp, 0, sizeof(dp));
  for (int i = 1; i <= n; i++) {
    dp[i] = a[i];
    int sum1 = b[i - 1], diff = c[i - 1] - b[i - 1];
    for (int j = i - 2; j >= 1; j--) {
      dp[i] = max(dp[i], (a[i] + sum1 + diff + dp[j]));
      sum1 += b[j];
      diff = max(diff, (c[j] - b[j]));
    }
    dp[i] = max(dp[i], (a[i] + sum1));
  }
  int sum1 = b[n];
  for (int j = n - 1; j >= 1; j--) {
    dp[j] = dp[j] + sum1;
    sum1 += b[j];
  }
  int ans = 0;
  for (int j = 1; j <= n; j++) {
    ans = max(ans, dp[j]);
  }
  cout << ans << "\n";
}
