#include <bits/stdc++.h>
using namespace std;
inline bool checkBit(long long n, int i) { return n & (1LL << i); }
inline long long setBit(long long n, int i) {
  return n | (1LL << i);
  ;
}
inline long long resetBit(long long n, int i) { return n & (~(1LL << i)); }
int dx[] = {0, 0, +1, -1};
int dy[] = {+1, -1, 0, 0};
inline bool EQ(double a, double b) { return fabs(a - b) < 1e-9; }
inline bool EQ2(double a, double b) { return fabs(a - b) < 1e-7; }
int dp[3010][2];
int a[3010], b[3010], c[3010];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) cin >> a[i];
  for (int i = 0; i < n; ++i) cin >> b[i];
  for (int i = 0; i < n; ++i) cin >> c[i];
  dp[n - 1][0] = a[n - 1];
  dp[n - 1][1] = b[n - 1];
  for (int i = n - 2; i >= 0; --i) {
    dp[i][1] = max(dp[i + 1][1] + b[i], dp[i + 1][0] + c[i]);
    dp[i][0] = max(dp[i + 1][1] + a[i], dp[i + 1][0] + b[i]);
  }
  cout << dp[0][0];
  return 0;
}
