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