#include <bits/stdc++.h>
using namespace std;
const int N = 3005;
int f[N][2];
int a[N], b[N], c[N];
int main() {
  int n;
  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;
  }
  f[2][0] = b[1];
  f[2][1] = a[1];
  for (int i = 3; i <= n; ++i) {
    f[i][0] = max(f[i - 1][0] + b[i - 1], f[i - 1][1] + c[i - 1]);
    f[i][1] = max(f[i - 1][0] + a[i - 1], f[i - 1][1] + b[i - 1]);
  }
  printf("%d\n", max(f[n][0] + a[n], f[n][1] + b[n]));
  return 0;
}
