#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 = 1234567891;
int N;
char c[205];
ll A, B, C, dp[205][205], h[205][205];
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 i = N; i >= 1; i--)
for(int k = i; k <= N; k++)
{
for(int j = i + 1; j <= k; j++)
dp[i][k] = min(dp[i][k], dp[j][k] + (j - i) * A);
ll cur = dp[i][k] + B + C, pre = k;
// cout << "copy: " << i << ' ' << k << " initial " << cur << '\n';
for(int j = k + 1; j <= N; j++)
{
cur += A;
if(pre < j - k + i && h[j - k + i][j] == h[i][k])
{
cur += -(k - i + 1) * A + C;
pre = j;
}
// cout << "copy: " << i << ' ' << k << " to " << i << ' ' << j << " cost " << cur << '\n';
dp[i][j] = min(dp[i][j], cur);
}
}
/* 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';
}
