#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n;
  cin >> n;
  long long int a[n];
  for (long long int i = 0; i < n; i++) cin >> a[i];
  long long int b[n];
  for (long long int i = 0; i < n; i++) cin >> b[i];
  long long int c[n];
  for (long long int i = 0; i < n; i++) cin >> c[i];
  long long int dp0[n];
  long long int dp1[n];
  dp0[n - 1] = a[n - 1];
  dp1[n - 1] = b[n - 1];
  for (long long int i = n - 2; i >= 0; i--) {
    dp0[i] = max(a[i] + dp1[i + 1], dp0[i + 1] + b[i]);
    dp1[i] = max(b[i] + dp1[i + 1], dp0[i + 1] + c[i]);
  }
  cout << dp0[0] << "\n";
  return 0;
}
