#include <bits/stdc++.h>
#define INF 1000000000000000000
#define N 2505
using namespace std;
typedef long long ll;

int n, lcp[N][N], pr[N][N];
ll A, B, C, f[N][N];
char s[N];

int main ()
{
    // freopen("0test.in", "r", stdin);
    // freopen("0test.out", "w", stdout);

    scanf("%d", &n);
    scanf("%s", s+1);
    scanf("%lld %lld %lld", &A, &B, &C);

    for (int i=n; i>=1; i--) {
        for (int j=i-1; j>=1; j--) {
            lcp[i][j]=min(i-j, (s[i]==s[j] ? (lcp[i+1][j+1]+1) : 0));
            if (!pr[i][lcp[i][j]]) {
                pr[i][lcp[i][j]]=j;
            }
        }
        for (int j=n; j>=0; j--) {
            pr[i][j]=max(pr[i][j], pr[i][j+1]);
        }
    }

    for (int i=n; i>=1; i--) {
        for (int j=i; j<=n; j++) { f[i][j]=INF; }
    }
    for (int i=n; i>=1; i--) {
        for (int j=i; j<=n; j++) {
            int len=j-i+1;
            f[i][j]=min(f[i][j], min(f[i][j-1], f[i+1][j])+A);
            int p=i;
            for (int k=1; k<=(j/len); k++) {
                p=pr[p][len];
                if (!p) { break; }
                f[p][j]=min(f[p][j], (k+1)*C+(j-p+1-(k+1)*(j-i+1))*A+f[i][j]+B);
            }
        }
    }

    printf("%lld\n", f[1][n]);

    return 0;
}