#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#define vi vector<int>
#define ve vector
#define ll long long
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define onbit __builtin_popcount
#define ii pair<int,int>
#define vvi vector<vi>
#define vii vector<ii>
#define gii greater<ii>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define INF 1e18
#define eps 1e-7
#define eps1 1e-2
#define optimise ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define MAX_A 1e5+5
using namespace std;
using namespace __gnu_pbds;
template <class T>
using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll MOD = (1LL << 61) - 1;
const int nax = 1e5+5;
const int MAX_VAL = 1e6+1;
double PI=3.14159265359;
int arx[8]={1,0,0,-1,-1,-1, 1, 1};
int ary[8]={0,1,-1, 0, 1,-1,-1, 1};
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
const int d=41;
int main(){
optimise;
/*#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif*/
//setIO("dec");
ll n,a,b,c;
string s;
cin>>n>>s>>a>>b>>c;
s="#"+s;
long long hash[n+1][n+1];
long long dp[n+1][n+1];
memset(hash,0,sizeof hash);
for (int i = 1; i <= n; ++i)
{
for (int j = i; j <= n ; ++j)
{
hash[i][j]=(hash[i][j-1]*26+s[j]-'a')%MOD;
}
for (int j = 0; j <= n; ++j)
{
dp[i][j]=1e18;
}
dp[i][i]=a;
}
for (ll h = 1; h <= n; ++h)
{
vector<pair<ll,ll>> cand;
for (int i = 1; i <= n-h+1; ++i)
{
dp[i][i+h-1]=min(dp[i][i+h-1],min(dp[i][i+h-2],dp[i+1][i+h-1])+a);
cand.pb({hash[i][i+h-1],i});
}
sort(cand.begin(),cand.end());
for(auto u:cand){
ll x=1;
ll i=u.se;
while(true){
int pos=lower_bound(cand.begin(),cand.end(),mp(u.fi,i+h))-cand.begin();
if(pos<cand.size()&&cand[pos].fi==u.fi){
i=cand[pos].se;
x++;
//cout <<h<<" "<<i<<endl;
dp[u.se][i+h-1]=min(dp[u.se][i+h-1],dp[u.se][u.se+h-1] + b + c*x + a*(i+h-u.se-x*h));
}else break;
}
}
}
cout <<dp[1][n]<<endl;
}
