#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
#define cerr if(false)cerr
const ll MAX_N = 2510;
ll n, a, b, c;
string str;
ll dp[MAX_N][MAX_N];
const ll mod1 = 1e9 + 7, mod2 = 2e9 + 9;
const ll base1 = 37, base2 = 127;
ll state[MAX_N];
int par[MAX_N];
template<class T, class T2> bool chkmin(T &a, const T2 &b) { return a > b ? a = b, 1 : 0; }
signed main() {
cin >> n >> str >> a >> b >> c;
for(ll i = 0; i < n; i ++) {
for(ll j = 0; j < n; j ++) {
dp[i][j] = (j - i + 1ll) * a;
}
}
for(ll len = 1; len <= n; len ++) {
ll hsh1 = 0, hsh2 = 0;
ll pw1 = 1, pw2 = 1;
for(ll i = 0; i < len; i ++) {
ll now = str[i] - 'a' + 1;
hsh1 = (hsh1 * base1 + now) % mod1;
hsh2 = (hsh2 * base2 + now) % mod2;
if(i != 0) {
pw1 = (pw1 * base1) % mod1;
pw2 = (pw2 * base2) % mod2;
}
}
state[0] = hsh1 + hsh2 * mod1;
for(ll i = 1; i + len - 1 < n; i ++) {
ll now = str[i + len - 1] - 'a' + 1;
hsh1 = (
(hsh1 - pw1 * (ll)(str[i - 1] - 'a' + 1ll))
% mod1 * base1 % mod1 + mod1 + now
) % mod1;
hsh2 = (
(hsh2 - pw2 * (ll)(str[i - 1] - 'a' + 1ll))
% mod2 * base2 % mod2 + mod2 + now
) % mod2;
state[i] = hsh1 + hsh2 * mod1;
}
map<ll, ll> mp;
for(ll i = 0; i + len - 1 < n; i ++) {
chkmin(dp[i][i + len - 1], dp[i + 1][i + len - 1] + a);
chkmin(dp[i][i + len - 1], dp[i][i + len - 2] + a);
if(i - len >= 0) {
mp[state[i - len]] = i - len;
}
if(mp.find(state[i]) != mp.end()) {
par[i] = mp[state[i]];
} else {
par[i] = -1;
}
int curr = par[i], cnt = 2;
while(curr != -1) {
int r = i + len - 1;
dp[curr][r] = min(dp[curr][r], dp[i][i + len - 1] + (r - curr + 1 - cnt * len) * a + b + cnt * c);
curr = par[curr];
cnt ++;
}
}
}
cout << dp[0][n - 1] << endl;
return 0;
}
