#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ii pair<int,int>
#define fi first
#define se second
#define endl '\n'
#define puf push_front
#define pof pop_front
#define pub push_back
#define pob pop_back
#define lb lower_bound
#define ub upper_bound
#define rep(x,s,e) for (int x=(s)-((s)>(e));x!=(e)-((s)>(e));((s)<(e))?x++:x--)
#define all(x) (x).begin(),(x).end()
#define sz(x) (int) (x).size()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n;
string s;
int a,b,c;
int memo[2505][2505]; //the answer
int nxt[2505][2505]; //(length,index)
void proc(vector<int> v,int len){
sort(all(v));
reverse(all(v));
int idx=-1;
for (auto it:v){
if (it+len<=v[idx+1]) idx++;
if (idx!=-1) nxt[len][it]=v[idx];
}
//cout<<len<<": "<<endl;
//for (auto it:v) cout<<it<<" "; cout<<endl;
}
signed main(){
cin.tie(0);
cout.tie(0);
cin.sync_with_stdio(false);
cin>>n>>s;
cin>>a>>b>>c;
vector<int> idx;
rep(x,0,n) idx.pub(x);
sort(all(idx),[](int i,int j){ //poor man's suffix array
return s.substr(i,n-i)<s.substr(j,n-j);
});
//for (auto it:idx) cout<<it<<" "; cout<<endl;
memset(nxt,-1,sizeof(nxt));
rep(x,1,n+1){
vector<int> temp;
for (auto it:idx) if (it+x<=n){
if (!temp.empty() && s.substr(temp.back(),x)!=s.substr(it,x)){
proc(temp,x);
temp.clear();
}
temp.pub(it);
}
proc(temp,x);
}
//rep(x,1,n+1){
//rep(y,0,n) cout<<nxt[x][y]<<" "; cout<<endl;
//}
memset(memo,1,sizeof(memo));
rep(x,0,n) memo[x][x]=a;
rep(len,1,n+1){
rep(l,0,n+1-len){
int r=l+len-1;
assert(memo[l][r]<=1e13);
if (l!=0) memo[l-1][r]=min(memo[l-1][r],memo[l][r]+a);
if (r!=n-1) memo[l][r+1]=min(memo[l][r+1],memo[l][r]+a);
int curr=l;
int num=1;
while (nxt[len][curr]!=-1){
curr=nxt[len][curr];
num++;
int r2=curr+len-1;
memo[l][r2]=min(memo[l][r2],
memo[l][r]+b+num*c+(r2-l+1-num*len)*a);
}
}
}
cout<<memo[0][n-1]<<endl;
}
