#include <bits/stdc++.h>
using namespace std;
const int N = 12345;
int a[N], b[N], c[N], dp[N][2][2];
int solve(int idx, int left, int right) {
  if (dp[idx][left][right] != -1) return dp[idx][left][right];
  int ans = 0;
  if (idx == 0) {
    if (left == 0 && right == 0)
      ans = a[idx];
    else if (right == 1)
      ans = b[idx];
    else
      ans = -1e9;
  } else {
    if (left == 0 && right == 0) {
      ans = a[idx] + max(solve(idx - 1, 0, 1), solve(idx - 1, 1, 1));
    } else if (left == 0 && right == 1) {
      ans = b[idx] + max(solve(idx - 1, 0, 1), solve(idx - 1, 1, 1));
    } else if (left == 1 && right == 0) {
      ans = b[idx] + max(solve(idx - 1, 0, 0), solve(idx - 1, 1, 0));
    } else if (left == 1 && right == 1) {
      ans = c[idx] + max(solve(idx - 1, 0, 0), solve(idx - 1, 1, 0));
    }
  }
  return dp[idx][left][right] = ans;
}
int main() {
  memset(dp, -1, sizeof(dp));
  int n, i;
  cin >> n;
  for (i = 0; i < n; i++) cin >> a[i];
  for (i = 0; i < n; i++) cin >> b[i];
  for (i = 0; i < n; i++) cin >> c[i];
  int ans = max(solve(n - 1, 0, 0), solve(n - 1, 1, 0));
  cout << (ans);
}
