#include <bits/stdc++.h>
using namespace std;
const int MAXN = 3010;
int a[MAXN], b[MAXN], c[MAXN];
int d[MAXN][2];
int main() {
  int n;
  while (~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]);
    d[1][0] = b[1];
    d[1][1] = a[1];
    for (int i = 2; i <= n; ++i) {
      d[i][0] = max(d[i - 1][0] + b[i], d[i - 1][1] + c[i]);
      d[i][1] = max(d[i - 1][0] + a[i], d[i - 1][1] + b[i]);
    }
    printf("%d\n", d[n][1]);
  }
  return 0;
}
