#include <bits/stdc++.h>
using namespace std;
const int MAX = 3005;
long long dp[MAX][2], a[MAX], b[MAX], c[MAX];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  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];
  dp[1][0] = a[1], dp[1][1] = b[1];
  for (int i = 2; i <= n; i++) {
    dp[i][0] = max(dp[i - 1][1] + a[i], dp[i - 1][0] + b[i]);
    dp[i][1] = max(dp[i - 1][1] + b[i], dp[i - 1][0] + c[i]);
  }
  cout << dp[n][0];
  return 0;
}
