#include <bits/stdc++.h>
using namespace std;
int n;
int a[10000], b[10000], c[10000], dp[10000][2];
void f(int ind) {
  if (ind == 0) {
    dp[ind][0] = a[ind];
    dp[ind][1] = a[ind];
    return;
  }
  if (ind == 1) {
    dp[ind][1] = max(dp[ind - 1][0], dp[ind - 1][1]) + b[ind];
    dp[ind][0] = a[ind] + b[ind - 1];
    return;
  }
  dp[ind][1] = max(dp[ind - 1][0], dp[ind - 1][1]) + b[ind];
  dp[ind][0] = max(dp[ind - 1][0] + b[ind - 1] - a[ind - 1],
                   dp[ind - 1][1] + c[ind - 1] - b[ind - 1]) +
               a[ind];
}
int main() {
  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];
  for (int i = 0; i < n; i++) {
    f(i);
  }
  cout << max(dp[n - 1][0], dp[n - 1][1]);
}
