#include <bits/stdc++.h>
using namespace std;
using namespace std;
long long int ans = 0;
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  ans += a / b;
  return gcd(b, a % b);
}
long long int mod = 1000000007;
long long int binpower(long long int a, long long int b) {
  long long int ans = 1;
  while (b > 0) {
    if (b & 1) ans = (ans * a) % mod;
    a = (a * a) % mod;
    b >>= 1;
  }
  return ans;
}
int n, a[3003], b[3003], c[3003];
long long int dp[3003][2];
long long int solve(int position, int state) {
  if (position == n - 1) {
    if (state == 0)
      return a[position];
    else
      return b[position];
  }
  if (dp[position][state] != -1) return dp[position][state];
  if (state == 1)
    dp[position][state] = max(solve(position + 1, 1) + b[position],
                              solve(position + 1, 0) + c[position]);
  else
    dp[position][state] = max(solve(position + 1, 1) + a[position],
                              solve(position + 1, 0) + b[position]);
  return dp[position][state];
}
int main() {
  int test = 1;
  while (test--) {
    cin >> n;
    for (int i = 0; i < n; i++) scanf("%d", &a[i]);
    for (int i = 0; i < n; i++) scanf("%d", &b[i]);
    for (int i = 0; i < n; i++) scanf("%d", &c[i]);
    for (int i = 0; i < n; i++)
      for (int j = 0; j < 2; j++) dp[i][j] = -1;
    cout << solve(0, 0);
  }
  return 0;
}
