#include <algorithm>
#include <bits/stdc++.h>
#include <ios>
using namespace std;
#define ll long long
#define ull unsigned long long
#define ld long double
#define ff first
#define ss second
#define ln "\n"
#define mp make_pair
#define pb push_back
#define INF (ll)2e18
#define MOD (ll)(1e9+7)
void solve(){
ll n; cin >> n;
string s; cin >> s;
ll ca, cb, cc; cin >> ca >> cb >> cc;
vector<vector<ll>> dp(n, vector<ll>(n));
for (ll i=0; i<n; i++){
dp[i][i]=ca;
}
for (ll i=1; i<n; i++){
for (ll l=0, r=i; r<n; l++,r++){
dp[l][r]=min(dp[l][r-1], dp[l+1][r])+ca;
for (ll m=l; m<r; m++){
ll rep=0;
for (ll k=m; k<=r; k++){
bool pos=1;
for (ll mi=l, ki=k-(m-l+1)+1; mi<=m; mi++, ki++){
if (s[mi]!=s[ki]) pos=0;
}
if (pos) {
rep++; k+=(m-l+1); k--;
}
}
// if (rep>1) cout << l << " - " << r << " - " << m << ": " << rep << ln;
dp[l][r]=min(dp[l][r], dp[l][m]+cb+cc*(rep)+ca*(r-l+1-(m-l+1)*(rep)));
}
}
}
cout << dp[0][n-1] << ln;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(nullptr);
#ifdef LOCAL
auto start = chrono::high_resolution_clock::now();
#endif
ll t=1;
// cin >> t;
for (ll __c=1; __c<=t; __c++) solve();
#ifdef LOCAL
auto duration = chrono::duration_cast<chrono::microseconds>(chrono::high_resolution_clock::now() - start);
cout << setprecision(0) << fixed << "time: " << (double)duration.count()/1000.0 << " milliseconds" << endl;
#endif
}
