#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define F first
#define S second
using namespace std;
const ll base = 29, mod = 462'779'347'772'851;
int N;
char c[2505];
ll A, B, C, dp[2505][2505], h[2505][2505], nxt[2505][2505];
signed main()
{
cin >> N;
for(int i = 1; i <= N; i++)
cin >> c[i];
cin >> A >> B >> C;
for(int i = 1; i <= N; i++)
for(int j = i; j <= N; j++)
{
dp[i][j] = A * (j - i + 1);
h[i][j] = (h[i][j - 1] * base + c[j] - 'a') % mod;
}
for(int l = 1; l <= N; l++)
{
map<ll, int> mp;
for(int i = N - l + 1; i >= 1; i--)
if(i + 2 * l - 1 <= N)
{
mp[h[i + l][i + 2 * l - 1]] = i + l;
nxt[i][i + l - 1] = mp[h[i][i + l - 1]];
// cout << "[" << i << ", " << i + l - 1 << "] -> [" << nxt[i][i + l - 1] << "]\n";
}
}
for(int i = N; i >= 1; i--)
for(int k = i; k <= N; k++)
{
dp[i][k] = min({dp[i][k], dp[i + 1][k] + A, dp[i][k - 1] + A});
ll base = dp[i][k] + B, j = nxt[i][k], t = 2;
for(; j != 0; j = nxt[j][j + k - i])
{
dp[i][j + k - i] = min(dp[i][j + k - i], base + t * C + (j + k - i - i + 1 - t * (k - i + 1)) * A);
t++;
}
}
/* for(int i = 1; i <= N; i++)
for(int j = 1; j <= N; j++)
if(j < i) cout << "- ";
else cout << dp[i][j] << " \n"[N == j];
*/
cout << dp[1][N] << '\n';
}
