#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
const ll INF = 1e18;
ll dp[2500][2500];
int main()
{
int n;
string s;
ll a,b,c;
cin>>n>>s>>a>>b>>c;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
dp[i][j] = INF;
}
}
for(int i=0;i<n;i++)dp[i][i] = a+b;
for(int len=0;len<n;len++){
for(int i=0;i+len<n;i++){
int r = i+len;
if(dp[i][r] == INF)continue;
//cout<<i<<" "<<r<<" "<<dp[i][r]<<'\n';
if(r+1<n)dp[i][r+1] = min(dp[i][r] + a,dp[i][r+1]);
if(i)dp[i-1][r] = min(dp[i][r]+a,dp[i-1][r]);
ll cur = c;
for(int j=i+1+len;j+len<n;j++){
//cout<<cur<<'\n';
bool ok = 1;
for(int k=0;k<=len;k++){
if(s[j+k] != s[i+k]){
ok = 0;
break;
}
}
if(!ok)cur+=a;
else{
//cout<<i<<" "<<r<<" "<<j<<" "<<j+len<<" "<<cur+b<<'\n';
cur+=c;
dp[i][j+len] = min(dp[i][j+len],dp[i][r] + cur+b);
j+=len;
}
}
}
}
cout<<dp[0][n-1] - b<<'\n';
}
