#include <algorithm>
#include <cstdint>
#include <iostream>
#include <string>
#define EVAL(x) cout << #x " = " << x << "\n"

namespace {
using std::cin;
using std::cout;
using std::int64_t;

template <typename T>
inline void CheckMin(T &x, const T &y) {
  if (y < x) x = y;
}

const int kMaxN = 2505;
const int64_t kInf = 1.0e18;
int n, a, b, c;
int lcp[kMaxN][kMaxN], next[kMaxN][kMaxN];
int64_t f[kMaxN][kMaxN];
std::string s;

void InitLcp() {
  for (int i = n; i; --i) {
    for (int j = n; j; --j) {
      lcp[i][j] = (s[i] == s[j]) * (lcp[i + 1][j + 1] + 1);
    }
  }
}

void InitNext() {
  for (int i = 1; i <= n; ++i) {
    int p = i;

    for (int j = 1; j <= n - i + 1; ++j) {
      while (p <= n && (p < i + j || lcp[i][p] < j)) ++p;
      next[i][j] = p;
    }
  }
}

void Dp() {
  for (int i = 1; i <= n; ++i) {
    std::fill(f[i] + i + 1, f[i] + n + 1, kInf), f[i][i] = a;
  }

  for (int l = n; l >= 1; --l) {
    for (int r = l; r <= n; ++r) {
      if (l < r) CheckMin(f[l][r], std::min(f[l + 1][r], f[l][r - 1]) + a);
      int len = r - l + 1, occur = 1;

      for (int p = next[l][len]; p <= n; p = next[p][len]) {
        int q = p + len - 1;
        ++occur;
        CheckMin(f[l][q], f[l][r] + b + int64_t{c} * occur +
                              int64_t{a} * ((q - l + 1) - len * occur));
      }
    }
  }
}
}  // namespace

int main() {
  cin.tie(nullptr);
  std::ios::sync_with_stdio(false);
  cin >> n >> s >> a >> b >> c, s = std::string(" ").append(s);
  InitLcp();
  InitNext();
  Dp();
  cout << f[1][n] << "\n";
  return 0;
}