#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll dp[31][31][31][31];
bool pre[31][31][31][31];
string s; ll a, b, c, n;
ll ans (int l1, int r1, int l2, int r2) {
ll &ret = dp[l1][r1][l2][r2];
if (ret != -1) return ret;
/*cout << (l1 == 0 ? "?" : s.substr(l1, r1 - l1 + 1)) << " ";
cout << (l2 == 0 ? "?" : s.substr(l2, r2 - l2 + 1)) << " ";
cout << '\n';*/
if (l1 == 1 && r1 == n) return ret = 0;
ret = 1e18;
if (l1 && r1 != n) ret = min(ret, a + ans(l1, r1 + 1, l2, r2));
if (!l1) {
for (int i = 1; i <= n; i++) ret = min(ret, a + ans(i, i, l2, r2));
}
if (l1) ret = min(ret, b + ans(0, 0, l1, r1));
if (l1 && l2 && r1 + (r2 - l2 + 1) <= n && pre[r1 + 1][r1 + r2 - l2 + 1][l2][r2]) {
ret = min(ret, c + ans(l1, r1 + r2 - l2 + 1, l2, r2));
}
if (!l1 && l2) {
for (int i = 1; i + (r2 - l2) <= n; i++) {
if (pre[i][i + r2 - l2][l2][r2]) ret = min(ret, c + ans(i, i + r2 - l2, l2, r2));
}
}
return ret;
}
int main () {
memset(dp, -1, sizeof(dp));
cin >> n >> s >> a >> b >> c;
s.insert(s.begin(), '0');
for (int i = 1; i <= n; i++) {
for (int j = i; j <= n; j++) {
for (int l = 1; l <= n; l++) {
for (int m = l; m <= n; m++) {
if (m - l != j - i) continue;
pre [i][j][l][m] = 1;
for (int t = i; t <= j; t++) {
pre[i][j][l][m] &= s[t] == s[l + t - i];
}
}
}
}
}
cout << ans(0, 0, 0, 0) << '\n';
}
