#include <bits/stdc++.h>
using namespace std;

#define int long long

const int N=2505;
const int P1=12321;
const int P2=131;

char s[N];
unsigned long long h1[N],p1[N],h2[N],p2[N];
pair <unsigned long long,unsigned long long> num[N*N];
int val[N][N],nex[N][N],dp[N][N];
vector <int> pos[3200000];

unsigned long long Hash1(int l,int r)
{
	return h1[r]-h1[l-1]*p1[r-l+1];
}

unsigned long long Hash2(int l,int r)
{
	return h2[r]-h2[l-1]*p2[r-l+1];
}

signed main()
{
	int n,A,B,C;
	cin >> n;
	scanf("%s",s+1);
	cin >> A >> B >> C;
	p1[0]=p2[0]=1;
	for(int i=1;i<=n;i++)
	{
		h1[i]=h1[i-1]*P1+s[i];
		p1[i]=p1[i-1]*P1;
		h2[i]=h2[i-1]*P2+s[i];
		p2[i]=p2[i-1]*P2;
	}

	int cnt=0;
	for(int i=1;i<=n;i++)
		for(int j=i;j<=n;j++)
			num[++cnt]=make_pair(Hash1(i,j),Hash2(i,j));

	sort(num+1,num+cnt+1);
	cnt=unique(num+1,num+cnt+1)-num-1;

	for(int i=1;i<=n;i++)
		for(int j=i;j<=n;j++)
			val[i][j]=lower_bound(num+1,num+cnt+1,make_pair(Hash1(i,j),Hash2(i,j)))-num;

	for(int i=1;i<=n;i++)
		for(int j=i;j<=n;j++)
			pos[val[i][j]].push_back(i);

	for(int i=1;i<=cnt;i++)
		pos[i].push_back(n+1);

	for(int i=1;i<=n;i++)
		for(int j=i;j<=n;j++)
			nex[i][j]=pos[val[i][j]][lower_bound(pos[val[i][j]].begin(),pos[val[i][j]].end(),j+1)-pos[val[i][j]].begin()];

	for(int i=n;i>=1;i--)
	{
		for(int j=i;j<=n;j++)
			dp[i][j]=dp[i+1][j]+A;

		for(int j=1;j<=n-i+1;j++)
		{
			int cnt=0;
			for(int k=i;k<=n-j+1;k=nex[k][k+j-1])
			{
				cnt++;
				dp[i][k+j-1]=min(dp[i][k+j-1],dp[k][k+j-1]+B+(k+j-i-cnt*j)*A+cnt*C);
			}
		}

		for(int j=i;j<=n;j++)
			dp[i][j]=min(dp[i][j],dp[i][j-1]+A);
	}

	printf("%lld\n",dp[1][n]);
	return 0;
}