#include<bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define isz(x) ((int)x.size())
#define sumof(x) accumulate(all(x), 0ll)
const int N=2510;
int f[N][N], add, cut, paste, n;
int g[N][N];
string s;
void precalc(){
for (int t=1; t<=n; ++t){
map<string, int> mp;
for (int r=t; r<=n; ++r){
string s1=s.substr(r-t+1, t);
g[r][t]=mp.count(s1)?mp[s1]:-1;
if (r-t+1>=t){
string s2=s.substr(r-t+1-t+1, t);
mp[s2]=r-t+1;
}
}
}
}
int count(int l, int r, int t){
if (r-l+1<t) return 0;
int pos=g[r][t];
return count(l, pos, t)+1;
}
int dp(int l, int r){
if (l>r) return 0;
if (f[l][r]!=-1) return f[l][r];
int res=dp(l, r-1)+add;
for (int t=l; t<=r; ++t){
int cnt=count(l, r, r-t+1);
if (cnt!=1) res=min(res, dp(t, r)+cut+cnt*paste+add*(r-l+1-cnt*(r-t+1)));
}
return f[l][r]=res;
}
void solve(){
memset(f, -1, sizeof f);
cin >> n >> s;
s=" "+s;
precalc();
cin >> add >> cut >> paste;
cout << dp(1, n);
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int ntests=1;
// cin >> ntests;
for (int i=1; i<=ntests; ++i) solve();
return 0;
}
