#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
long long POW(long long a, long long b, long long MMM = MOD) {
  long long ret = 1;
  for (; b; b >>= 1, a = (a * a) % MMM)
    if (b & 1) ret = (ret * a) % MMM;
  return ret;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) {
  if (a == 0 || b == 0) return a + b;
  return a * (b / gcd(a, b));
}
int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};
int ddx[] = {0, 0, 1, 1, 1, -1, -1, -1}, ddy[] = {1, -1, 1, 0, -1, 1, 0, -1};
int a[3000], b[3000], c[3000];
int d[3000][2];
int main() {
  int n;
  scanf("%d", &n);
  for (int(i) = (0); (i) <= (n - 1); (i) += (1)) scanf("%d", a + i);
  for (int(i) = (0); (i) <= (n - 1); (i) += (1)) scanf("%d", b + i);
  for (int(i) = (0); (i) <= (n - 1); (i) += (1)) scanf("%d", c + i);
  d[0][0] = a[0], d[0][1] = b[0];
  for (int(i) = (1); (i) <= (n - 1); (i) += (1)) {
    d[i][0] = max(a[i] + d[i - 1][1], b[i] + d[i - 1][0]);
    d[i][1] = max(b[i] + d[i - 1][1], c[i] + d[i - 1][0]);
  }
  printf("%d", d[n - 1][0]);
}
