#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
#define MAX 2510
#define MAXS 20
#define INF 1000000000000000001
#define MOD 998244353
#define bb ' '
#define ln '\n'
#define Ln '\n'
ll dp[MAX][MAX];
#define base 29
ll mpow[MAX];
ll hv[MAX];
signed main() {
ios::sync_with_stdio(false), cin.tie(0);
int N;
cin >> N;
string s;
cin >> s;
ll A, B, C;
cin >> A >> B >> C;
int k, i, j;
mpow[0] = 1;
for (i = 0; i < N; i++) for (j = 0; j < N; j++) dp[i][j] = INF;
for (i = 1; i <= N; i++) mpow[i] = 1ll * mpow[i - 1] * base, mpow[i] %= MOD;
for (i = 0; i < N; i++) dp[i][i] = A;
for (k = 1; k <= N; k++) {
ll hash = 0;
for (i = 0; i < k; i++) hash *= base, hash += (s[i] - 'a'), hash %= MOD;
map<ll, vector<int>> vall;
for (i = 0; i < (N - k + 1); i++) {
vall[hash].push_back(i);
hv[i] = hash;
hash *= base;
if (i + k < N) hash += (s[i + k] - 'a');
hash -= 1ll * mpow[k] * (s[i] - 'a');
hash %= MOD;
while (hash < 0) hash += MOD;
}
for (i = 0; i < (N - k + 1); i++) {
j = i + k - 1;
dp[i][j] = min(dp[i][j], min(dp[i + 1][j], dp[i][j - 1]) + A);
ll h = hv[i];
int M = vall[h].size();
for (int p = 0; p < M; p++) {
int cnt = 1;
int l = vall[h][p];
int pv = vall[h][p];
for (int q = p + 1; q < M; q++) {
if (pv + k <= vall[h][q]) cnt++, pv=vall[h][q];
int r = vall[h][q] + k - 1;
dp[l][r] = min(dp[l][r], dp[i][j] + B + C * cnt + A * ((ll)r - l + 1 - (ll)cnt * ((ll)j - i + 1)));
}
}
}
}
cout << dp[0][N - 1] << ln;
}
