#include <bits/stdc++.h>
using namespace std;
int dp[3010][4];
int a[3010], b[3010], c[3010];
int main() {
  int i, j, n;
  cin >> n;
  for (i = 1; i <= n; i++) cin >> a[i];
  for (i = 1; i <= n; i++) cin >> b[i];
  for (i = 1; i <= n; i++) cin >> c[i];
  for (i = 1; i <= n; i++) {
    if (i == 1) {
      dp[i][0] = a[i];
      dp[i][1] = b[i];
      dp[i][2] = -1e9;
      dp[i][3] = -1e9;
    } else {
      dp[i][0] = max(dp[i - 1][1], dp[i - 1][3]) + a[i];
      dp[i][1] = max(dp[i - 1][1], dp[i - 1][3]) + b[i];
      dp[i][2] = max(dp[i - 1][0], dp[i - 1][2]) + b[i];
      dp[i][3] = max(dp[i - 1][2], dp[i - 1][0]) + c[i];
    }
  }
  printf("%d\n", max(dp[n][0], dp[n][2]));
  return 0;
}
