#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
constexpr long long mod = 100000008;
const long long INF = mod * mod;
const long double eps = 1e-12;
const long double pi = acosl(-1.0);
long long mod_pow(long long x, long long n, long long m = mod) {
  if (n < 0) {
    long long res = mod_pow(x, -n, m);
    return mod_pow(res, m - 2, m);
  }
  if (abs(x) >= m) x %= m;
  if (x < 0) x += m;
  long long res = 1;
  while (n) {
    if (n & 1) res = res * x % m;
    x = x * x % m;
    n >>= 1;
  }
  return res;
}
struct modint {
  long long n;
  modint() : n(0) { ; }
  modint(long long m) : n(m) {
    if (n >= mod)
      n %= mod;
    else if (n < 0)
      n = (n % mod + mod) % mod;
  }
  operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint& a, modint b) {
  a.n += b.n;
  if (a.n >= mod) a.n -= mod;
  return a;
}
modint operator-=(modint& a, modint b) {
  a.n -= b.n;
  if (a.n < 0) a.n += mod;
  return a;
}
modint operator*=(modint& a, modint b) {
  a.n = ((long long)a.n * b.n) % mod;
  return a;
}
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, long long n) {
  if (n == 0) return modint(1);
  modint res = (a * a) ^ (n / 2);
  if (n % 2) res = res * a;
  return res;
}
long long inv(long long a, long long p) {
  return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }
modint operator/=(modint& a, modint b) {
  a = a / b;
  return a;
}
const int max_n = 100;
modint fact[max_n], factinv[max_n];
void init_f() {
  fact[0] = modint(1);
  for (int i = 0; i < max_n - 1; i++) {
    fact[i + 1] = fact[i] * modint(i + 1);
  }
  factinv[max_n - 1] = modint(1) / fact[max_n - 1];
  for (int i = max_n - 2; i >= 0; i--) {
    factinv[i] = factinv[i + 1] * modint(i + 1);
  }
}
modint comb(int a, int b) {
  if (a < 0 || b < 0 || a < b) return 0;
  return fact[a] * factinv[b] * factinv[a - b];
}
modint combP(int a, int b) {
  if (a < 0 || b < 0 || a < b) return 0;
  return fact[a] * factinv[a - b];
}
long long costup[400][400];
long long costdown[400][400];
long long dp[400][400];
long long dp2[400][400];
void solve() {
  int n;
  cin >> n;
  vector<long long> cost(n + 1);
  for (int i = 1; i <= n; i++) cin >> cost[i];
  vector<int> a(n);
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int l = n - 1; l >= 0; l--) {
    costup[l][l] = costdown[l][l] = 0;
    for (int i = l + 1; i < n; i++) {
      costup[l][i] = -INF;
      for (int j = l; j < i; j++)
        if (a[j] == a[i] - 1) {
          long long ncost = costup[l][j];
          if (i - j >= 2) ncost += dp[j + 1][i - 1];
          costup[l][i] = max(costup[l][i], ncost);
        }
      costdown[l][i] = -INF;
      for (int j = l; j < i; j++)
        if (a[j] == a[i] + 1) {
          long long ncost = costdown[l][j];
          if (i - j >= 2) ncost += dp[j + 1][i - 1];
          costdown[l][i] = max(costdown[l][i], ncost);
        }
    }
    dp[l][l] = cost[1];
    for (int j = l + 1; j < n; j++) dp[l][j] = -INF;
    for (int i = l; i < n; i++)
      for (int j = i; j < n; j++) {
        long long val = costup[l][i] + costdown[i][j];
        int len = a[i] - a[l] + a[i] - a[j] + 1;
        if (len <= 0 || len > n) continue;
        val += cost[len];
        dp[l][j] = max(dp[l][j], val);
      }
    for (int r = l + 1; r < n; r++) {
      for (int c = l; c < r; c++) {
        dp[l][r] = max(dp[l][r], dp[l][c] + dp[c + 1][r]);
      }
    }
  }
  for (int l = n - 1; l >= 0; l--) {
    dp2[l][l] = max(0ll, cost[1]);
    for (int j = l + 1; j < n; j++) dp2[l][j] = -INF;
    for (int i = l; i < n; i++)
      for (int j = i; j < n; j++) {
        long long val = costup[l][i] + costdown[i][j];
        int len = a[i] - a[l] + a[i] - a[j] + 1;
        if (len <= 0 || len > n) continue;
        val += cost[len];
        dp2[l][j] = max(dp2[l][j], val);
      }
    for (int r = l + 1; r < n; r++) {
      for (int c = l; c < r; c++) {
        dp2[l][r] = max(dp2[l][r], dp2[l][c] + dp2[c + 1][r]);
      }
    }
  }
  cout << dp2[0][n - 1] << "\n";
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  solve();
  return 0;
}
