#include <bits/stdc++.h>
using namespace std;
const int BASE = 77777;
const int md = 1e9 + 7;
int ckadd(int a, int b) {
return a + b < md ? a + b : a + b - md;
}
int cksub(int a, int b) {
return a >= b ? a - b : a - b + md;
}
int ckmul(int a, int b) {
return a * 1LL * b % md;
}
int qpow(int x, int k) {
int ret = 1;
while (k) {
if (k & 1) {
ret = ckmul(ret, x);
}
x = ckmul(x, x);
k >>= 1;
}
return ret;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
string s;
cin >> s;
int a, b, c;
cin >> a >> b >> c;
vector<int> pw(n);
pw[0] = 1;
for (int i = 1; i < n; i++) {
pw[i] = ckmul(pw[i - 1], BASE);
}
vector<int> dv(n);
dv[n - 1] = qpow(pw[n - 1], md - 2);
for (int i = n - 2; i >= 0; i--) {
dv[i] = ckmul(dv[i + 1], BASE);
}
vector<int> pref(n);
for (int i = 0; i < n; i++) {
if (i > 0) {
pref[i] = pref[i - 1];
}
pref[i] = ckadd(pref[i], ckmul(pw[i], s[i] - 'a'));
}
auto Get = [&](int L, int R) {
int ret = pref[R];
if (L > 0) {
ret = cksub(ret, pref[L - 1]);
}
return ckmul(ret, dv[L]);
};
const long long inf = (long long) 1e18;
vector<vector<long long>> dp(n, vector<long long>(n, inf));
for (int len = 0; len < n; len++) {
vector<int> to(n, -1);
map<int, int> mp;
for (int l = n - len - 1; l >= 0; l--) {
int r = l + len;
if (r + 1 + len < n) {
mp[Get(r + 1, r + 1 + len)] = r + 1;
}
int h = Get(l, r);
if (mp[h] != 0) {
to[l] = mp[h];
}
if (l == r) {
dp[l][r] = a;
}
if (l < r) {
dp[l][r] = min(dp[l][r], min(dp[l + 1][r], dp[l][r - 1]) + a);
}
{
int x = l;
int cnt = 1;
while (to[x] != -1) {
x = to[x];
cnt += 1;
dp[l][x + len] = min(dp[l][x + len], dp[l][r] + b + c * 1LL * cnt + a * 1LL * ((x + len - l + 1) - cnt * (len + 1)));
}
}
}
}
cout << dp[0][n - 1] << '\n';
return 0;
}
