#include <bits/stdc++.h>
using namespace std;
int dp[3001][2];
int main() {
  int n, i, j;
  int a[3000];
  int b[3000];
  int c[3000];
  scanf("%d", &n);
  for (i = 0; i < n; i++) scanf("%d", &a[i]);
  for (i = 0; i < n; i++) scanf("%d", &b[i]);
  for (i = 0; i < n; i++) scanf("%d", &c[i]);
  c[0] = b[0];
  c[n - 1] = b[n - 1];
  for (i = 0; i <= n; i++) {
    for (j = 0; j < 2; j++) {
      dp[i][j] = -1;
    }
  }
  dp[0][0] = 0;
  for (i = 0; i < n; i++) {
    for (j = 0; j < 2; j++) {
      if (dp[i][j] == -1) continue;
      dp[i + 1][j] = max(dp[i + 1][j], dp[i][j] + b[i]);
      if (j == 0) {
        dp[i + 1][1] = max(dp[i + 1][1], dp[i][j] + a[i]);
      } else {
        dp[i + 1][0] = max(dp[i + 1][0], dp[i][j] + c[i]);
      }
    }
  }
  printf("%d\n", dp[n][1]);
  return 0;
}
