#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 3001;
int n;
int dp[MAX_N][2];
int a[MAX_N], b[MAX_N], c[MAX_N];
void solve() {
  dp[2][0] = b[1], dp[2][1] = a[1];
  for (int i = 3; i <= n; ++i) {
    dp[i][0] = max(dp[i - 1][0] + b[i - 1], dp[i - 1][1] + c[i - 1]);
    dp[i][1] = max(dp[i - 1][0] + a[i - 1], dp[i - 1][1] + b[i - 1]);
  }
  int ans = max(dp[n][0] + a[n], dp[n][1] + b[n]);
  printf("%d\n", ans);
}
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) {
    scanf("%d", &a[i]);
  }
  for (int i = 1; i <= n; ++i) {
    scanf("%d", &b[i]);
  }
  for (int i = 1; i <= n; ++i) {
    scanf("%d", &c[i]);
  }
  if (n == 1) {
    printf("%d\n", a[1]);
    return 0;
  }
  solve();
  return 0;
}
