#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
//#include<bits/extc++.h>
//__gnu_pbds
#define int ll
const int N = 2505;
ll dp[N][N]; string s;
int a,b,c;
int h[N][N];
const int MOD = 712271226;
const int P = 101;
int hsh[N];
int ppow[N];
int get(int l,int r){
ll ans = hsh[r];
ans = (ans-(1LL*hsh[l-1]*ppow[r-l+1])%MOD)%MOD;
if(ans<0) ans+=MOD;
return ans;
}
signed main(){
ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
int n;cin>>n;
cin>>s;
cin>>a>>b>>c;
ppow[0]=1;
for(int i=1;i<=n;i++){
hsh[i] = (1LL*hsh[i-1]*P)%MOD;
hsh[i]+=(s[i-1]-'a');
hsh[i]%=MOD;
ppow[i] = (1LL*P*ppow[i-1])%MOD;
}
for(int len=1;len<=n;len++){
vector<pair<int,int> > hsharr;
for(int i=1;i+len-1<=n;i++){
hsharr.push_back({get(i,i+len-1),i});
}
sort(hsharr.begin(),hsharr.end());
int k = hsharr.size();
int l = 0;int r = 0;
int head = 0;
for(;l<k;l++){
while(r<k && hsharr[r].first==hsharr[l].first) r++;
while(head<r && hsharr[head].second<=hsharr[l].second+len-1) head++;
if(head<r) h[hsharr[l].second][len]=hsharr[head].second;
}
}
/*for(int l=1;l<=n;l++){
for(int i=1;i<=n;i++){
cout<<h[i][l]<<" ";
}
cout<<"\n";
}*/
for(int i=0;i<=n;i++){
for(int j=i;j<=n;j++){
dp[i][j] = 1LL*(j-i+1)*a+b;
}
}
for(int l=1;l<n;l++){
// cout<<l<<":";
for(int i=1;i+l-1<=n;i++){
int j = i+l-1;
dp[i-1][j] = min(dp[i][j]+a,dp[i-1][j]);
dp[i][j+1] = min(dp[i][j]+a,dp[i][j+1]);
int cnt =2;
int k = h[i][l];
for(;k+l-1<=n && k>0 ;k=h[k][l]){
dp[i][k+l-1] = min(dp[i][k+l-1],dp[i][i+l-1]+1LL*c*cnt+1LL*a*((k+l-i)-(cnt*l))+b);
cnt++;
}
}
}
/*for(int i=1;i<=n;i++){
for(int j=i;j<=n;j++) cout<<dp[i][j]<<" ";
cout<<"\n";
}*/
//cout<<n<<"\n";
//cout<<s<<"\n";
cout<<dp[1][n]-b<<"\n";
return 0;
}
/*
18
aababbbababbbaabbb
100
1
10
806020000
*/
