#include <bits/stdc++.h>
using namespace std;
const int MAXINT = 1 << 31 - 1;
const int MAXN = 3005;
int dp0[MAXN], dp1[MAXN];
int a[MAXN], b[MAXN], c[MAXN];
int n;
int main() {
  while (scanf("%d", &n) != -1) {
    for (int i = (1); i < (n + 1); i += 1) {
      scanf("%d", a + i);
    }
    for (int i = (1); i < (n + 1); i += 1) {
      scanf("%d", b + i);
    }
    for (int i = (1); i < (n + 1); i += 1) {
      scanf("%d", c + i);
    }
    memset(dp0, 0, sizeof(dp0)), memset(dp1, 0, sizeof(dp1));
    dp0[n] = a[n], dp1[n] = b[n];
    for (int i = (n - 1); i > (0); i -= 1) {
      dp0[i] = max(dp0[i + 1] + b[i], dp1[i + 1] + a[i]);
      dp1[i] = max(dp0[i + 1] + c[i], dp1[i + 1] + b[i]);
    }
    int res = dp0[1];
    printf("%d\n", res);
  }
  return 0;
}
