#include <bits/stdc++.h>
using namespace std;
#define REP(i, j, k) for (int i = j; i < k; i++)
#define RREP(i, j, k) for (int i = j; i >= k; i--)
template <class T>
bool mnto(T &a, const T b) {return a > b ? a = b, 1 : 0;}
template <class T>
bool mxto(T &a, const T b) {return a < b ? a = b, 1 : 0;}
typedef long long ll;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
#define ALL(x) x.begin(), x.end()
#define SZ(x) (int) x.size()
#define pb push_back
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<ll> vll;
#ifndef DEBUG
#define cerr if(0) cerr
#endif
const int MAXN = 2505;
const int INF = 1000000005;
const ll LINF = 1000000000000000005;
int n;
string s;
int a, b, c;
ll dp[MAXN][MAXN];
int main() {
#ifndef DEBUG
ios::sync_with_stdio(0), cin.tie(0);
#endif
cin >> n;
cin >> s;
cin >> a >> b >> c;
RREP (i, n - 1, 0) {
REP (j, i, n) {
dp[i][j] = dp[i + 1][j] + a;
REP (k, i, j) {
ll cost = dp[i][k] + b;
int len = k - i + 1;
REP (l, i, j + 1) {
bool pos = 1;
if (l + len - 1 <= j) {
REP (m, 0, len) {
if (s[i + m] != s[l + m]) {
pos = 0;
break;
}
}
} else {
pos = 0;
}
if (pos) {
l += len - 1;
cost += c;
} else {
cost += a;
}
}
mnto(dp[i][j], cost);
}
cerr << i << ' ' << j << ": " << dp[i][j] << '\n';
}
}
cout << dp[0][n - 1] << '\n';
return 0;
}
