#include<bits/stdc++.h>
#define fi first
#define se second
#define mk make_pair
#define pub emplace_back
#define pob pop_back
using namespace std;
const int N=2510;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
const ull P=131;
int n;ll va,vb,vc;
ull hsh[N],cf[N];
char s[N];
pii to[N][N];
ll dp[N][N];
ull ask(int l,int r){
	return hsh[r]-hsh[l-1]*cf[r-l+1];
}
vector<pii> v[N];int vs=0;
pii gt(int id,int dd){
	if(v[id].empty()||v[id].front().se>=dd) return mk(0,0);
	int l=0,r=(int)v[id].size()-1,mid;
	while(l<r){
		mid=l+r+1>>1;
		if(v[id][mid].se<dd) l=mid;
		else r=mid-1;
	}
	return v[id][l];
}
void init(){
	cf[0]=1;for(int i=1;i<=n;i++) cf[i]=cf[i-1]*P;
	hsh[0]=0;for(int i=1;i<=n;i++) hsh[i]=hsh[i-1]*P+(s[i]-'a'+1);
	
	unordered_map<ull,int> mp;
	for(int len=1;len<=n;len++){
		while(mp.size()) mp.erase(mp.begin());
		vs=0;
		for(int l=1;l+len-1<=n;l++){
			int r=l+len-1;
			ull st=ask(l,r);
			auto it=mp.find(st);int id;
			if(it==mp.end()) id=mp[st]=++vs,v[vs].clear();
			else id=it->se;
			to[l][r]=gt(id,l);
			v[id].pub(mk(l,r));
		//	cout<<l<<" "<<r<<":"<<to[l][r].fi<<" "<<to[l][r].se<<endl;
		}
	}
}
void chkmi(ll &x,ll y){x=min(x,y);}
int main(){
	//freopen("dd.in","r",stdin);
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	cin>>n>>s+1>>va>>vb>>vc;
	init();
	memset(dp,0x3f,sizeof(dp));
	for(int r=1;r<=n;r++){
		chkmi(dp[r][r],va);
		for(int blo=1;blo<=r;blo++){
			int bl=r-blo+1;
			if(blo>1){
				chkmi(dp[bl][r],dp[bl+1][r]+va);
				chkmi(dp[bl][r],dp[bl][r-1]+va);
			}
	//		cout<<bl<<","<<r<<":"<<dp[bl][r]<<endl;
			ll nv=dp[bl][r],cs=0;
			while(bl){
				cs++;
				chkmi(dp[bl][r],(r-bl+1-cs*blo)*va+cs*vc+vb+nv);
				bl=to[bl][bl+blo-1].fi;
			}
		}
	}
	cout<<dp[1][n]<<endl;
	return 0;
}