#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
const ll INF = 1e18;
ll dp[2500][2500];
int nxt[2500][2500];
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);
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;
nxt[i][j] = n;
}
}
for(int i=0;i<n;i++){
vector<int>z(n,0);
vector<bool>hav(n,0);
string t = s.substr(i,n-i);
int cur = 1;
int l = 0,r = 0;
//cout<<"at"<<" "<<i<<'\n';
for(int j=1;j<n-i;j++){
if(j<=r)z[j] = min(r-j+1,z[j-l]);
while(j+z[j]<n-i && t[j+z[j]] == t[z[j]])z[j]++;
if(j+z[j]-1>r){
l = j;
r = j+z[j]-1;
}
while(cur<=j && cur<=z[j]){
//cout<<i<<" "<<i+cur-1<<" "<<i+j<<'\n';
nxt[i][i+cur-1] = i+j;
cur++;
}
}
/*
for(int j=0;j<n;j++)cout<<z[j]<<" ";
cout<<'\n';
for(int j=i;j<n;j++)cout<<nxt[i][j]<<" ";
cout<<'\n';
* */
}
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;
int pos = i;
while(pos<n){
int jump = nxt[pos][pos+len];
if(jump>=n)break;
cur+=(jump-(pos+len)-1)*1LL*a;
cur+=c;
dp[i][jump+len] = min(dp[i][jump+len],dp[i][r] + cur+b);
pos = jump;
}
}
}
cout<<dp[0][n-1] - b<<'\n';
}
