#include <bits/stdc++.h>
using namespace std;
const int maxn = 3005;
int a[maxn];
int b[maxn];
int c[maxn];
int dp[4][maxn];
int main() {
  ios::sync_with_stdio(false);
  int n;
  int ans;
  scanf("%d", &n);
  for (int i = 1; i < n + 1; ++i) scanf("%d", &a[i]);
  for (int i = 1; i < n + 1; ++i) scanf("%d", &b[i]);
  for (int i = 1; i < n + 1; ++i) scanf("%d", &c[i]);
  if (n == 1) {
    ans = a[1];
    printf("%d\n", ans);
    return 0;
  } else if (n == 2) {
    ans = max(a[1] + b[2], b[1] + a[2]);
    printf("%d\n", ans);
    return 0;
  }
  int i, j, k;
  for (i = 1; i <= n; ++i) {
    if (i == 1) {
      dp[1][i] = a[i];
      dp[3][i] = b[i];
    } else if (i == n) {
      dp[2][i] = max(dp[2][i - 1], dp[3][i - 1]) + a[i];
      dp[3][i] = max(dp[0][i - 1], dp[1][i - 1]) + b[i];
    } else {
      dp[0][i] = max(dp[2][i - 1], dp[3][i - 1]) + a[i];
      dp[1][i] = max(dp[0][i - 1], dp[1][i - 1]) + b[i];
      dp[2][i] = max(dp[2][i - 1], dp[3][i - 1]) + b[i];
      dp[3][i] = max(dp[0][i - 1], dp[1][i - 1]) + c[i];
    }
  }
  ans = max(dp[2][n], dp[3][n]);
  printf("%d\n", ans);
  return 0;
}
