#include <bits/stdc++.h>
using namespace std;
const int inf = 2000000000;
static inline int Rint() {
  struct X {
    int dig[256];
    X() {
      for (int i = '0'; i <= '9'; ++i) dig[i] = 1;
      dig['-'] = 1;
    }
  };
  static X fuck;
  int s = 1, v = 0, c;
  for (; !fuck.dig[c = getchar()];)
    ;
  if (c == '-')
    s = 0;
  else if (fuck.dig[c])
    v = c ^ 48;
  for (; fuck.dig[c = getchar()]; v = v * 10 + (c ^ 48))
    ;
  return s ? v : -v;
}
template <typename T>
static inline void cmax(T& a, const T& b) {
  if (b > a) a = b;
}
template <typename T>
static inline void cmin(T& a, const T& b) {
  if (b < a) a = b;
}
const int maxn = 3005;
int val[maxn][3];
int dp[maxn][2];
int main() {
  const int n = Rint();
  for (int i = 0; i < 3; ++i)
    for (int j = 1; j <= n; ++j) val[j][i] = Rint();
  if (n == 1) {
    printf("%d\n", val[1][0]);
    return 0;
  }
  if (n == 2) {
    int u = val[1][0] + val[2][1];
    int v = val[1][1] + val[2][0];
    printf("%d\n", max(u, v));
    return 0;
  }
  dp[n][0] = val[n][0];
  dp[n][1] = val[n][1];
  for (int i = n - 1; i >= 1; --i) {
    dp[i][0] = max(val[i][0] + dp[i + 1][1], val[i][1] + dp[i + 1][0]);
    dp[i][1] = max(val[i][1] + dp[i + 1][1], val[i][2] + dp[i + 1][0]);
  }
  printf("%d\n", dp[1][0]);
  return 0;
}
