#include <bits/stdc++.h>
using namespace std;
int a[100000];
int b[100000];
int c[100000];
int dp[3][100000];
int main() {
  ios_base::sync_with_stdio(false);
  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];
  if (n == 1) {
    cout << a[1];
    return 0;
  }
  dp[0][1] = a[1];
  dp[1][1] = b[1];
  for (int i = 2; i <= n - 1; i++) {
    dp[0][i] = max(a[i] + dp[1][i - 1], b[i] + dp[0][i - 1]);
    dp[1][i] = max(b[i] + dp[1][i - 1], c[i] + dp[0][i - 1]);
  }
  cout << max(dp[0][n - 1] + b[n], dp[1][n - 1] + a[n]);
}
