#include <bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(0);cin.tie(0);
typedef long long ll;
#define f first
#define s second
#define MOD 998244353
#define LOGN 21
const ll MAXN = 2550;
const ll P = 39;
ll N, A, B, C;
string s;
ll hashes[MAXN], to[MAXN][MAXN], dp[MAXN][MAXN], powP[MAXN];
ll f(int l, int r) {
ll h = (hashes[r] - powP[r-l+1] * hashes[l - 1] % MOD) % MOD;
if (h < 0)
h += MOD;
return h;
}
vector<int> occ[MAXN];
map<ll, deque<int>> mp;
int main() {
fast
cin >> N >> s >> A >> B >> C;
s = "#" + s;
powP[0] = 1;
for (int i = 1; i <= N; i++)
powP[i] = (powP[i-1] * P) % MOD;
for (int i = 1; i <= N; i++)
hashes[i] = (hashes[i-1] * P + (s[i] - 'a' + 1)) % MOD;
for (int len = 1; len <= N; len++) {
mp.clear();
for (int j = N-len+1; j >= 1; j--) {
ll h = f(j, j + len - 1);
while (mp[h].size() >= 2 && mp[h][1] > j + len - 1)
mp[h].pop_front();
to[j][len] = (mp[h].size() == 0 ? 0 : mp[h].front());
if (to[j][len] <= j + len - 1)
to[j][len] = 0;
if (to[j][len])
occ[j].push_back(len);
mp[h].push_back(j);
}
}
for (int i = 1; i <= N; i++) {
for (int j = 1; j <= N; j++)
dp[i][j] = 1e14;
}
for (int l = N; l >= 1; l--) {
dp[l][l] = A;
for (int r = l+1; r <= N; r++)
dp[l][r] = min(dp[l][r], min(dp[l+1][r] + A, dp[l][r-1] + A));
for (auto len : occ[l]) {
int cnt = 1;
int now = to[l][len];
ll base = dp[l][l+len-1];
while (now != 0) {
int total = now - l - cnt * len;
dp[l][now + len - 1] = min(dp[l][now + len - 1], total * A + B + C * (cnt + 1) + base);
cnt++;
now = to[now][len];
}
}
for (int r = l+1; r <= N; r++)
dp[l][r] = min(dp[l][r], min(dp[l+1][r] + A, dp[l][r-1] + A));
}
cout << dp[1][N] << "\n";
}
