#include <bits/stdc++.h>
using namespace std;
#pragma comment(linker, "/STACK:255000000")
bool firstout = 1;
template <class T>
void minn(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
T maxx(T &a, T b) {
  if (a < b) a = b;
  return a;
}
int madd(int &a, int b) {
  a += b;
  if (a >= 1000000009) a -= 1000000009;
  return a;
}
int msub(int &a, int b) {
  a -= b;
  if (a < 0) a += 1000000009;
  return a;
}
int mmult(int &a, int b) { return a = (long long)a * b % 1000000009; }
int mdiv(long long a, long long b, long long m) {
  a = (a % m + m) % m;
  b = (b % m + m) % m;
  if (a % b == 0) return a / b;
  return (a + m * mdiv(-a, m, b)) / b;
}
int n, m;
int A[155];
char S[155];
int D[155][155];
int DD[155][155][155];
int fndd(int i, int j, int l) {
  int &res = DD[i][j][l];
  if (res != -1) return res;
  if (j < i) return res = A[2 * l];
  res = -1012345678;
  if (l > 0) maxx(res, A[2 * l] + fndd(i, j, 0));
  if (i == j) return maxx(res, A[2 * l + 1]);
  if (S[i] == S[j]) maxx(res, fndd(i + 1, j - 1, l + 1));
  int k;
  for (k = (i); k < (j); ++k) maxx(res, fndd(i, k, 0) + fndd(k + 1, j, l));
  for (k = (i + 1); k < (j + 1); ++k)
    maxx(res, fndd(i, k - 1, l) + fndd(k, j, 0));
  return res;
}
int fnd(int i, int j) {
  int &res = D[i][j];
  if (res >= 0) return res;
  res = max(0, fndd(i, j, 0));
  int k;
  for (k = (i); k < (j); ++k) maxx(res, fnd(i, k) + fnd(k + 1, j));
  return res;
}
int main() {
  int i, j, k;
  char c;
  int a, d;
  int ts;
  for (ts = 1; scanf("%"
                     "d",
                     &(n)) > 0;
       ++ts) {
    A[0] = 0;
    for (i = (1); i < (n + 1); ++i)
      scanf(
          "%"
          "d",
          &(A[i]));
    for (i = (1); i < (n + 1); ++i)
      if (A[i] == -1) A[i] = -1012345678;
    scanf(
        "%"
        "s",
        &(S));
    for (i = (0); i < (n); ++i)
      for (j = (0); j < (n); ++j) D[i][j] = -1;
    for (i = (0); i < (n); ++i)
      for (j = (0); j < (n); ++j)
        for (k = (0); k < (n + 1); ++k) DD[i][j][k] = -1;
    int res = fnd(0, n - 1);
    printf(
        "%"
        "d",
        (res));
    printf("\n"), firstout = 1;
  }
  return 0;
}
