#include <iostream>
#include <vector>
#include <array>
#include <map>
#define ll long long
using namespace std;
string S;
const ll M = 1e9 + 7, M2 = 1e9 + 11;
map <array<ll, 2>, ll> mp;
array <ll, 2> X[2510][2510];
ll n, a, b, c, s, s2, base = 37, base2 = 41, p, p2, dp[2510][2500], nx[2510][2510];
int main() {
cin.tie(0);
ios::sync_with_stdio(0);
cin >> n >> S >> a >> b >> c;
for (ll i=0; i<n; ++i) {
s = s2 = 0, p = p2 = 1;
for (ll j=i; j<n; ++j) {
(s += (S[j]-'a'+1) * p % M) %= M;
(p *= base) %= M;
(s2 += (S[j]-'a'+1) * p2 % M) %= M;
(p2 *= base) %= M;
X[i][j] = {s, s2};
}
}
for (ll len=0; len<n; ++len) {
mp.clear();
for (ll i=n-len-1; i>=0; --i) {
if (i+2*len+1 < n) {
mp[X[i+len+1][i+2*len+1]] = i+len+1;
}
if (mp.count(X[i][i+len])) nx[i][i+len] = mp[X[i][i+len]];
else nx[i][i+len] = -1;
}
for (ll i=0; i+len<n; ++i) {
if (len) {
dp[i][i+len] = min(dp[i][i+len], min(dp[i][i+len-1], dp[i+1][i+len]));
}
s = 0;
ll j = i;
while (true) {
ll k = nx[j][j+len];
++s;
if (k == -1) break;
dp[i][k+len] = min(dp[i][k+len], dp[i][i+len] + b + (s+1) * c - (s * (len+1) * a));
j = k;
}
}
}
cout << a*n + dp[0][n-1] << '\n';
}
