#include <bits/stdc++.h>
using namespace std;
const int MAXN = 3 * 1000;
int a[MAXN], b[MAXN], c[MAXN], dp[MAXN][2];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int i = 0; i < n; i++) cin >> b[i];
  for (int i = 0; i < n; i++) cin >> c[i];
  dp[n - 1][0] = a[n - 1];
  dp[n - 1][1] = b[n - 1];
  for (int i = n - 2; i > -1; i--) {
    dp[i][0] = max(a[i] + dp[i + 1][1], b[i] + dp[i + 1][0]);
    dp[i][1] = max(b[i] + dp[i + 1][1], c[i] + dp[i + 1][0]);
  }
  cout << dp[0][0];
  return 0;
}
