#include <bits/stdc++.h>
using namespace std;
#define int long long
char arr[2505];
int A,B,C;
int mem[2505*1505];
int id[2505][2505];
int ct = 1;
struct node{
int nid, len;
vector<int> vals;
node*ch[26];
vector<int> decomp[15];
node(int _len){
nid = ct++;
len = _len;
for (int x = 0; x<26; x++){
ch[x] = 0;
}
}
void construct(){
//printf("call construct len %lld\n",len);
for (int x = 0; x<vals.size(); x++){
decomp[0].push_back(lower_bound(vals.begin(),vals.end(),vals[x]+len)-vals.begin());
}
decomp[0].push_back(vals.size());
for (int x = 1; x<15; x++){
for (int y = 0; y<=vals.size(); y++){
decomp[x].push_back(decomp[x-1][decomp[x-1][y]]);
}
}
}
void constructall(){
construct();
for (int x = 0; x<26; x++){
if (ch[x]!=0){
ch[x]->constructall();
}
}
}
int cntocc(int st, int en){
//printf("call cntocc %lld %lld, len %lld\n",st,en,len);
int cur = lower_bound(vals.begin(),vals.end(),st)-vals.begin();
int ans = 1;
int r = upper_bound(vals.begin(),vals.end(),en-len)-vals.begin();
for (int x = 14; x>=0; x--){
if (decomp[x][cur]<r){
ans += (1<<x);
cur = decomp[x][cur];
}
}
return ans;
}
}*rt;
node* pt[2505][2505];
int cntocc(int a, int b, int st, int en){
return pt[a][b]->cntocc(st,en);
}
int func(int a, int b){
if (mem[id[a][b]]!=-1) return mem[id[a][b]];
if (a==b) return 0;
int ans = func(a+1,b)+A;
for (int x = 1; x<b-a; x++){
int t = func(a,a+x);
int t2 = cntocc(a,a+x,a,b);
ans = min(ans,t+B+t2*C+(b-a-x*t2)*A);
if (t2==1) break;
}
//printf("func %lld %lld = %lld\n",a,b,ans);
return mem[id[a][b]] = ans;
}
main(){
int n;
scanf("%lld",&n);
for (int x = 0; x<n; x++){
scanf(" %c",&arr[x]);
}
scanf("%lld%lld%lld",&A,&B,&C);
memset(mem,-1,sizeof(mem));
for (int x = 0; x<n; x++){
if (rt==0){
rt = new node(0);
}
node *cur = rt;
for (int y = x+1; y<=n; y++){
if (cur->ch[arr[y-1]-'a']==0){
cur->ch[arr[y-1]-'a'] = new node(y-x);
}
cur = cur->ch[arr[y-1]-'a'];
cur->vals.push_back(x);
pt[x][y] = cur;
id[x][y] = cur->nid;
}
}
rt->constructall();
printf("%lld",func(0,n));
}
