#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 2505;
int n;
string s;
int a, b, c;
long long f[maxn][maxn];
vector<int> ft[maxn];
vector<pair<int, int>> cand[maxn][maxn];
vector<int> z_function(string s) {
int n = s.length();
vector<int> z(n);
for (int i = 1, l = 0, r = 0; i < n; ++i) {
if (i <= r)
z[i] = min(r - i + 1, z[i - l]);
while (i + z[i] < n && s[z[i]] == s[i + z[i]])
++z[i];
if (i + z[i] - 1 > r) {
l = i;
r = i + z[i] - 1;
}
}
return z;
}
void mnz(long long &x, long long y) {
x = min(x, y);
}
void solve() {
cin >> n >> s >> a >> b >> c;
for (int i = 0; i < n; ++i) {
string v = s.substr(i, n - i);
vector<int> z = z_function(v);
ft[i].resize(n - i + 1, -1);
for (int j = n - i - 1; j >= 0; --j) {
if (j >= z[j]) {
ft[i][z[j]] = j;
} else {
ft[i][j] = j;
}
}
for (int j = n - i - 1; j >= 0; --j) {
if (ft[i][j] == -1 || ft[i][j] > ft[i][j + 1]) {
if (ft[i][j + 1] != -1) ft[i][j] = ft[i][j + 1];
}
}
// debug(i, ft[i]);
}
for (int l = n - 1; l >= 0; --l) {
for (int i = l; i < n; ++i) {
int prf = i - l + 1;
if (ft[l][prf] == -1) continue;
int cur = l + ft[l][prf], cnt = 1;
// debug(l, prf, cur);
long long cost = f[l][i] + b;
while (cur < n - l + 1 and cur != -1) {
++cnt;
cand[l][cur + prf - 1].emplace_back(prf, cnt);
if (ft[cur][prf] == -1) break;
cur = cur + ft[cur][prf];
}
}
}
for (int l = n - 1; l >= 0; --l) {
for (int r = l; r < n; ++r) {
f[l][r] = min(f[l][r - 1], f[l + 1][r]) + a;
for (auto [len, cnt] : cand[l][r]) {
long long cost = f[l][l + len - 1] + b;
mnz(f[l][r], cost + 1ll * cnt * c + 1ll * (r - l + 1 - cnt * len) * a);
// debug(l, r, len, cnt, f[l][r]);
}
// debug(l, r, f[l][r]);
}
}
cout << f[0][n - 1];
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
/*
7
abbabaa
1000000000
100000
10000000
*/
