#include <bits/stdc++.h>
using namespace std;
const int N = 3e3 + 3;
int n;
int mem[N][2];
int score[3][N];
int go(int i, int p) {
  if (i == n) {
    return score[p][n];
  }
  if (mem[i][p] != -1) {
    return mem[i][p];
  }
  int mx = 0;
  if (i == 1) {
    mx = max(mx, score[0][i] + go(i + 1, 1));
    mx = max(mx, score[1][i] + go(i + 1, 0));
  } else {
    if (p) {
      mx = max(mx, score[1][i] + go(i + 1, 1));
      mx = max(mx, score[2][i] + go(i + 1, 0));
    } else {
      mx = max(mx, score[0][i] + go(i + 1, 1));
      mx = max(mx, score[1][i] + go(i + 1, 0));
    }
  }
  return mem[i][p] = mx;
}
int main() {
  scanf("%d", &n);
  for (int i = 0; i < 3; i++) {
    for (int j = 1; j <= n; j++) {
      int x;
      scanf("%d", &score[i][j]);
    }
  }
  memset(mem, -1, sizeof mem);
  printf("%d\n", go(1, 0));
}
