#include<bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define epb emplace_back
using namespace std;
const int NMAX = 2501 + 1;
const int inf = 1e9 + 1;
const ll linf = 1e18 + 1;
ll h[NMAX];
const ll mod = 1e9 + 7;
const ll pr = 29;
ll po[NMAX];
string s;
void fil(){
int n = s.size();
h[0] = 0;
for(int i = 1; i <= n; i++){
ll x = s[i - 1] - 'a';
h[i] = h[i - 1] * 29 + x;
h[i] %= mod;
}
}
ll gethash(int l, int r){
ll x = h[r] - h[l - 1] * po[r - l + 1];
x %= mod;
x += mod;
x %= mod;
return x;
}
ll cnt[2501][2501];
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
po[0] = 1;
for(int i = 1; i <= 2500; i++){
po[i] = po[i - 1] * pr;
po[i] %= mod;
}
int n; cin >> n;
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
cnt[i][j] = linf;
}
}
cin >> s;
ll a, b, c; cin >> a >> b >> c;
fil();
for(int r = 1; r <= n; r++){
pii dp[n + 1];
for(int i = 1; i <= n; i++){
dp[i] = {inf, 0};
}
dp[1] = {r, 1};
cnt[r][r] = a;
for(int l = r - 1; l >= 1; l--){
for(int sz = 1; sz <= r - l + 1; sz++){
ll x = gethash(l, l + sz - 1);
ll y = gethash(r - sz + 1, r);
if(x == y){
if(dp[sz].f > l + sz - 1){
dp[sz].s++;
dp[sz].f = l;
}
}
}
cnt[l][r] = cnt[l][r - 1] + a;
for(int sz = 1; sz <= r - l + 1; sz++){
ll m = dp[sz].s;
ll val = cnt[r - sz + 1][r];
cnt[l][r] = min(cnt[l][r], (c - sz * a) * m + (r - l + 1) * a + val + b);
}
}
}
/*for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
if(cnt[i][j] == linf)cout << - 1 << " ";
else cout << cnt[i][j] << " ";
}
cout << "\n";
}*/
cout << cnt[1][n];
return 0;
}
