#pragma GCC optimize("Ofast","O3","unroll-loops")
#pragma GCC target("avx2")
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(),x.end()
#define x first
#define y second
#define endl '\n'
const int K=29,INF=1e18,mod=123456789098761;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;cin>>n;
vector<char> v(n+1);
for(int i=1;i<=n;i++){
cin>>v[i];
}
int A,B,C;cin>>A>>B>>C;
vector<vector<int>> h(n+2,vector<int>(n+2));
for(int i=1;i<=n;i++){
for(int j=i;j<=n;j++){
h[i][j]=h[i][j-1]*K+v[j]-'a'+1;
h[i][j]%=mod;
}
}
vector<vector<int>> dp(n+2,vector<int>(n+2,INF));
for(int i=1;i<=n;i++){
dp[i][i]=A;
}
for(int i=1;i<=n;i++){
map<int,int> mp;
vector<int> jump(n+1);
for(int j=1;j+i-1<=n;j++){
int k=j+i-1;
dp[j][k]=min({dp[j+1][k]+A,dp[j][k-1]+A,dp[j][k]});
int cnt=2;
if(j>i){
mp[h[j-i][j-1]]=j-i;
}
jump[j]=mp[h[j][k]];
int j1=jump[j];
while(j1!=0){
dp[j1][k]=min(dp[j1][k],dp[j][k]+B+cnt*C+(k-j1+1-cnt*i)*A);
cnt++;
j1=jump[j1];
}
}
}
cout<<dp[1][n]<<endl;
return 0;
}
