#include <bits/stdc++.h>
using namespace std;
int dp[3001][2], A[3001], B[3001], C[3001], n;
int main() {
  scanf("%d", &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++) dp[i][0] = dp[i][1] = -10000000;
  dp[n - 1][0] = A[n - 1], dp[n - 1][1] = B[n - 1];
  for (int i = n - 2; i >= 0; i--) {
    for (int l = 0; l < 2; l++) {
      if (l)
        dp[i][l] = max(dp[i + 1][l] + B[i], dp[i + 1][!l] + C[i]);
      else
        dp[i][l] = max(dp[i + 1][!l] + A[i], dp[i + 1][l] + B[i]);
    }
  }
  printf("%d\n", dp[0][0]);
}
