#include <bits/stdc++.h>
using namespace std;
#define st first
#define nd second
#define pb push_back
typedef long long ll;
typedef long double ld;
const ll P = 313LL;
const ll M = 694202137;
const ll I = (1LL<<31LL);
const int N = 2500 + 7;
ll A, B, C;
string s;
ll has[N], pot[N];
int nxt[N][N];
ll dp[N][N];
void Do(int n)
{
pot[0] = 1LL;
for(int i = 1; i <= n + 2; ++i)
pot[i] = (pot[i - 1] * P) % M;
for(int i = 1; i <= n; ++i)
has[i] = (has[i - 1] + (ll)(s[i] - 'a') * pot[i]) % M;
}
ll Get(int l, int r, int n)
{
ll a = has[r] - has[l - 1];
a += M; a %= M;
a = (a * pot[n - l]) % M;
return a;
}
void Calc(int n, int d)
{
map<ll, int> lst;
for(int i = n - d + 1; i >= 1; --i)
{
if(i + (2 * d) - 1 <= n)
lst[Get(i + d, i + (2 * d) - 1, n)] = i + d;
ll a = Get(i, i + d - 1, n);
if(lst.find(a) == lst.end())
lst[a] = n + 1;
nxt[i][d] = lst[a];
}
}
void Solve()
{
int n;
cin >> n;
cin >> s; s = '#' + s;
cin >> A >> B >> C;
for(int i = 1; i <= n; ++i)
for(int j = i; j <= n; ++j)
dp[i][j] = (ll)(j - i + 1) * A;
Do(n);
for(int i = 1; i < n; ++i)
Calc(n, i);
for(int d = 1; d <= n; ++d)
for(int i = 1; i <= n - d + 1; ++i)
{
int j = i + d - 1;
dp[i][j] = min(dp[i][j], min(dp[i + 1][j], dp[i][j - 1]) + A);
//cout << i << " " << j << " " << dp[i][j] << " " << nxt[i][d] << "\n";
if(d == n) continue;
ll a = dp[i][j] + B + C;
int p = i;
while(p <= n)
{
dp[i][p + d - 1] = min(dp[i][p + d - 1], a);
a += C + (ll)(nxt[p][d] - p - d) * A;
p = nxt[p][d];
}
}
cout << dp[1][n] << "\n";
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//int t; cin >> t;
//while(t--)
Solve();
return 0;
}
