//qoj3504
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

const int N = 2510;
int n;
char s[N];
ll A, B, C;
int lcp[N][N], nx[N][N];
ll f[N][N];

int main(){
	scanf("%d%s%lld%lld%lld", &n, s+1, &A, &B, &C);
	memset(nx, 0x3f, sizeof(nx));
	for(int i = n; i >= 1; -- i){
		lcp[i][i] = n - i + 1;
		for(int j = i + 1; j <= n; ++ j){
			if(s[i] == s[j]){
				lcp[i][j] = lcp[i+1][j+1] + 1;
			}
			nx[i][min(j, i+lcp[i][j])-1] = min(nx[i][min(j, i+lcp[i][j])-1], j);
		}
		for(int j = n; j >= i; -- j){
			nx[i][j] = min(nx[i][j], nx[i][j+1]);
		}
	}
	memset(f, 0x3f, sizeof(f));
	for(int len = 1; len <= n; ++ len){
		for(int l = 1; l + len - 1 <= n; ++ l){
			int r = l + len - 1;
			f[l][r] = min(f[l][r], A * (r - l + 1));
			f[l][r] = min(f[l][r], min(f[l+1][r], f[l][r-1]) + A);
			int p = nx[l][r], cnt = 1;
			while(p <= n){
				++ cnt;
				f[l][p+len-1] = min(f[l][p+len-1], f[l][r] + A * (p+len-l-cnt*len) + B + C * cnt);
				p = nx[p][p+len-1];
			}
		}
	}
	printf("%lld\n", f[1][n]);
	return 0;
}