#include <stdio.h>
#include <string.h>
#define N 2500
#define A 26
#define INF 0x3f3f3f3f3f3f3f3fLL
long long min(long long a, long long b) { return a < b ? a : b; }
int main() {
static char cc[N + 1];
static long long dp[N][N];
static int lcp[N + 1][N + 1], ii[N], jj[N], kk[A + 1];
int n, i, j, k, l, a;
long long u, v, w;
scanf("%d%s%lld%lld%lld", &n, cc, &u, &v, &w);
for (i = n - 1; i >= 0; i--)
for (j = n - 1; j >= 0; j--)
lcp[i][j] = cc[i] == cc[j] ? lcp[i + 1][j + 1] + 1 : 0;
for (i = 0; i < n; i++)
memset(dp[i] + i, 0x3f, (n - i + 1) * sizeof *dp[i]), dp[i][i] = u;
for (i = 0; i < n; i++)
ii[i] = i;
for (l = 1; l < n; l++) {
for (i = 0, j = 0; i < n - l + 1; i++) {
while (j < n - l + 1 && (j < i || lcp[ii[i]][ii[j]] >= l && ii[j] - ii[i] < l))
j++;
jj[ii[i]] = j < n - l + 1 && lcp[ii[i]][ii[j]] >= l ? ii[j] : -1;
}
for (i = 0; (j = i + l - 1) < n; i++) {
long long x = dp[i][j];
if (x == INF)
continue;
if (i > 0)
dp[i - 1][j] = min(dp[i - 1][j], x + u);
if (j + 1 < n)
dp[i][j + 1] = min(dp[i][j + 1], x + u);
for (j = jj[i], k = 2; j != -1; j = jj[j], k++)
dp[i][j + l - 1] = min(dp[i][j + l - 1], x + u * (j - i + l - k * l) + v + w * k);
}
memset(kk, 0, (A + 1) * sizeof *kk);
for (i = 0; i < n - l + 1; i++) {
j = --ii[i];
if (j < 0)
continue;
kk[cc[j] - 'a' + 1]++;
}
for (a = 1; a <= A; a++)
kk[a] += kk[a - 1];
for (i = 0; i < n - l + 1; i++)
if ((j = ii[i]) >= 0)
jj[kk[cc[j] - 'a']++] = j;
memcpy(ii, jj, (n - l) * sizeof *jj);
}
printf("%lld\n", dp[0][n - 1]);
return 0;
}
