#include <vector>
#include <iostream>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <string>
using namespace std;
#define v vector
#define ll long long
#define pii pair<int,int>
#define fi first
#define se second
int main(){
int N;
cin>>N;
string S;
cin>>S;
ll A,B,C;
cin>>A>>B>>C;
//non disjoint next occurence
v<v<v<int>>> immediateNext(N+1,v<v<int>>(N+1,v<int>(20,N)));
for(int l=0; l<N; l++){
for(int i=l+1; i<N; i++){
if(S[l]==S[i]){
immediateNext[l][1][0]=i;
break;
}
}
}
for(int s=2; s<=N; s++){
for(int l=0; l<=N-s; l++){
int nex=immediateNext[l][s-1][0];
while(nex<=N-s){
if(S[l+s-1]==S[nex+s-1]){
immediateNext[l][s][0]=nex;
break;
}
nex=immediateNext[nex][s-1][0];
}
}
}
//make jump pointers:
for(int i=1; i<20; i++){
for(int s=2; s<=N; s++){
for(int l=0; l<=N-s; l++){
immediateNext[l][s][i]=immediateNext[immediateNext[l][s][i-1]][s][i-1];
}
}
}
//make next occurence disjoint using jump pointers
v<v<int>> nextOccur(N, v<int>(N+1, N));
for(int l=0; l<N; l++){
for(int s=1; s<=N-l; s++){
int nex=l;
for(int i=19; i>=0; i--){
if(immediateNext[nex][s][i]<l+s){
nex=immediateNext[nex][s][i];
}
}
nextOccur[l][s] = immediateNext[nex][s][0];
}
}
v<v<ll>> dp(N, v<ll>(N,1e17));
for(int s=1; s<=N; s++){
for(int l=N-1; l>=0; l--){
dp[l][l]=A;
if(s!=1 && l+s-1<N){
dp[l][l+s-1] = min(dp[l][l+s-1], A+dp[l+1][l+s-1]);
dp[l][l+s-1] = min(dp[l][l+s-1], dp[l][l+s-1-1]+A);
}
int num=2, nex=nextOccur[l][s];
while(nex<N){
int r=nex+s-1;
dp[l][r] = min(dp[l][r], dp[l][l+s-1]+B+C*num+(r-l+1 - num*s)*A);
dp[l][r] = min(dp[l][r], A+dp[l+1][r]);
dp[l][r] = min(dp[l][r], dp[l][r-1]+A);
nex=nextOccur[nex][s];
num++;
}
}
}
cout<<dp[0][N-1]<<endl;
}
