#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(x) (x).begin(), (x).end()
const int N = 2507;
int n;
string s;
ll a, b, c;
ll dp[N][N];
int lcp[N][N], nxt[N][N];
int main() {
cin.tie(0)->sync_with_stdio(false);
cin >> n >> s >> a >> b >> c;
s = " " + s;
for (int i = n; i >= 1; i--)
for (int j = n; j > i; j--)
if (s[i] == s[j])
lcp[i][j] = min(lcp[i + 1][j + 1] + 1, j - i);
for (int i = 1; i <= n; i++) {
vector<int> bst(n + 1, n + 1);
int val = n + 1;
for (int j = n; j >= i; j--) {
nxt[i][j] = val;
bst[lcp[i][j]] = j;
if (lcp[i][j] >= j - i)
val = j;
val = min(val, bst[j - i]);
}
}
memset(dp, 0x3f, sizeof(dp));
for (int i = n; i >= 1; i--) {
dp[i][i] = a;
for (int j = i; j <= n; j++) {
dp[i - 1][j] = min(dp[i - 1][j], dp[i][j] + a);
dp[i][j + 1] = min(dp[i][j + 1], dp[i][j] + a);
int r = j;
ll cost = b + c;
while (nxt[r - (j - i)][r] <= n) {
int skip = nxt[r - (j - i)][r] - r - 1;
cost += a * skip + c;
r += skip + 1 + (j - i);
dp[i][r] = min(dp[i][r], dp[i][j] + cost);
}
}
}
cout << dp[1][n] << '\n';
return 0;
}
