// Skyqwq
#include <bits/stdc++.h>

#define pb push_back
#define fi first
#define se second
#define mp make_pair

using namespace std;

typedef pair<int, int> PII;
typedef long long LL;

template <typename T> bool chkMax(T &x, T y) { return (y > x) ? x = y, 1 : 0; }
template <typename T> bool chkMin(T &x, T y) { return (y < x) ? x = y, 1 : 0; }

template <typename T> void inline read(T &x) {
    int f = 1; x = 0; char s = getchar();
    while (s < '0' || s > '9') { if (s == '-') f = -1; s = getchar(); }
    while (s <= '9' && s >= '0') x = x * 10 + (s ^ 48), s = getchar();
    x *= f;
}

const int N = 2505, S = 13;

int n, lcp[N][N], L[N][N], R[N][N], nxt[N][N], la[N][N], jp[S][N][N];


char s[N];

LL f[N][N], A, B, C;

int main() {
    read(n);
    scanf("%s", s + 1);
    read(A), read(B), read(C);
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            if (s[i] == s[j]) lcp[i][j] = lcp[i - 1][j - 1] + 1;
        }
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 2, k = 0; j <= n - i + 1; j++) {
            while (k && s[k + i] != s[j + i - 1]) k = nxt[i][k];
            if (s[k + i] == s[j + i - 1]) ++k;
            nxt[i][j] = k;
        }
    }
    for (int i = 1; i <= n; i++) {
        int mx = 0;
        for (int j = 1; j <= i; j++) {
            for (int k = mx + 1; k <= lcp[j][i]; k++)
                L[i - k + 1][i] = j - k + 1, R[i - k + 1][i] = j;
            chkMax(mx, lcp[j][i]);
        }
        mx = 0;
        for (int j = i - 1; j; j--) {
            int lim = min(lcp[j][i], i - j);
            for (int k = mx + 1; k <= lim; k++)
                la[i - k + 1][i] = j;
            chkMax(mx, lim);
        }
    }
    for (int i = 1; i <= n; i++) {
        for (int j = i; j <= n; j++) {
            jp[0][i][j] = la[i][j];
            for (int k = 1; k < S && jp[k - 1][i][j]; k++) {
                jp[k][i][j] = jp[k - 1][jp[k - 1][i][j] - (j - i)][jp[k - 1][i][j]];
            }
        }
    }
    for (int Le = 1; Le <= n; Le++) {
        for (int l = 1, r = 0; (r = l + Le - 1) <= n; l++) {
            if (L[l][r] != l) {
                f[l][r] = f[L[l][r]][R[l][r]];
                continue;
            }
            LL &v = f[l][r];
            v = min(f[l + 1][r], f[l][r - 1]) + A;
            int len = r - l + 1;
            int i = nxt[l][r - l + 1];
            while (i) {
                if (i * 2 <= len) {
                    LL c = A * (r - l + 1), o = f[l][l + i - 1];
                    c += o + B;
                    c += 2 * (-i * A + C);
                    int x = r;
                    for (int o = S - 1; ~o; o--)
                        if (jp[o][x - i + 1][x] - i + 1 > l + i - 1)
                            c += (1 << o) * (-i * A + C), x = jp[o][x - i + 1][x];
                    chkMin(v, c);
                }
                i = nxt[l][i];
            }
        }
    }
    printf("%lld\n", f[1][n]);
    return 0;
}