#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n;
  cin >> n;
  long long int A[n + 1];
  long long int B[n + 1];
  long long int C[n + 1];
  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];
  long long int sum[n + 2][3];
  sum[0][0] = 0;
  sum[1][1] = A[1];
  sum[1][2] = A[1];
  if (n == 1) {
    cout << A[1] << endl;
    return 0;
  }
  sum[2][1] = A[1] + B[2];
  sum[2][2] = A[2] + B[1];
  for (int i = 3; i <= n; ++i) {
    long long a = A[i] + C[i - 1];
    long long b = B[i] + B[i - 1];
    sum[i - 1][1] = sum[i - 1][1] - B[i - 1];
    sum[i][2] = sum[i - 1][1] + a;
    sum[i][1] = sum[i - 1][1] + b;
    a = A[i] + B[i - 1];
    b = A[i - 1] + B[i];
    sum[i - 1][2] = sum[i - 1][2] - A[i - 1];
    sum[i][2] = max(sum[i][2], sum[i - 1][2] + a);
    sum[i][1] = max(sum[i][1], sum[i - 1][2] + b);
  }
  cout << max(sum[n][1], sum[n][2]) << endl;
  return 0;
}
