#include <bits/stdc++.h>
using namespace std;
const signed long int N = 3001, INF = 1000000000;
signed long int a[N], b[N], c[N], d[N][2];
signed long int answer;
void init() { freopen("input.txt", "r", stdin); }
void solve() {
  signed long int n, maximum, happiness, index;
  scanf("%li", &n);
  for (signed long int i = 0; i < n; ++i) {
    scanf("%li", &a[i]);
  }
  for (signed long int i = 0; i < n; ++i) {
    scanf("%li", &b[i]);
  }
  for (signed long int i = 0; i < n; ++i) {
    scanf("%li", &c[i]);
  }
  d[0][0] = a[0];
  d[0][1] = -INF;
  for (signed long int i = 1; i < n; ++i) {
    d[i][1] = max(d[i - 1][0], d[i - 1][1]) + b[i];
    d[i][0] = max(d[i - 1][0] - a[i - 1] + b[i - 1] + a[i],
                  d[i - 1][1] - b[i - 1] + c[i - 1] + a[i]);
  }
  answer = max(d[n - 1][0], d[n - 1][1]);
}
void output() { printf("%li", answer); }
int main() {
  solve();
  output();
  return 0;
}
