#include "bits/stdc++.h"
using namespace std;
#define int long long
const int N = 2507;
const int INF = 1e18;
struct node {
int child[26];
node() {
memset(child, 0, sizeof(child));
}
};
vector<node> tree;
int n, add, cop, paste;
int dp[N][N], nxt[N], val[N], mp[N * N];
string s;
void walk(int &j, int c) {
if (tree[j].child[c]) {
j = tree[j].child[c];
}
else {
int next_idx = tree.size();
tree[j].child[c] = next_idx;
tree.emplace_back();
j = next_idx;
}
}
int32_t main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> s >> add >> cop >> paste;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++)
dp[i][j] = INF;
}
tree.emplace_back();
s = " " + s;
for (int i = 1; i <= n; i++) {
memset(mp, 0, sizeof(mp));
for (int j = n - i + 1; j >= 1; j--) {
walk(val[j], s[j + i - 1] - 'a');
if (j + i + i - 1 <= n)
mp[val[j + i]] = j + i;
dp[j][i] = min({dp[j][i], dp[j][i - 1] + add, dp[j + 1][i - 1] + add});
nxt[j] = mp[val[j]];
int cur_pos = j;
int cost = dp[j][i] + cop + paste;
while (nxt[cur_pos]) {
cost += paste + add * (nxt[cur_pos] - cur_pos - i);
cur_pos = nxt[cur_pos];
dp[j][cur_pos + i - j] = min(dp[j][cur_pos + i - j], cost);
}
}
}
cout << dp[1][n] << "\n";
return 0;
}
