#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 25e2;
const ll inf = 1e18;
char v[N];
int lcp[N][N];
int nxt[N][N];
ll dp[N][N];
int main(){
int n;
cin>>n;
for(int i = 0;i < n;i++){
cin>>v[i];
}
int a,b,c;
cin>>a>>b>>c;
for(int i = n - 1;i >= 0;i--){
for(int j = n - 1;j >=0;j--){
if(v[i] == v[j]){
lcp[i][j] = 1 + ((i == n - 1 || j == n - 1)?0:lcp[i + 1][j + 1]);
}else lcp[i][j] = 0;
nxt[i][j] = n;
dp[i][j] = inf;
}
}
for(int i = n - 1;i >= 0;i--){
int k = i;
int j = i + 1;
while(k < n){
j = max(j,k + 1);
while(j < n && lcp[i][j] <= k - i){
j++;
}
nxt[i][k] = j;
k++;
}
}
for(int i = n - 1;i >= 0;i--){
for(int j = i;j < n;j++){
if(i == j)dp[i][j] = min(dp[i][j],(ll)a);
else dp[i][j] = min(dp[i][j],min(dp[i + 1][j],dp[i][j - 1]) + (ll)a);
///propogate
int k = j;
int cnt = 0;
int length = j - i + 1;
while(k < n){
cnt++;
//cout<<i<<' '<<j<<' '<<k<<' '<<dp[i][j] + b + c*cnt + a*(k - i + 1 - length*cnt)<<' '<<(k - i + 1 - length*cnt)<<'\n';
dp[i][k] = min(dp[i][k],dp[i][j] + b + 1ll*c*cnt + 1ll*a*(k - i + 1 - length*cnt));
k = nxt[k - length + 1][k] + length - 1;
}
//cout<<dp[i][j]<<' '<<nxt[i][j]<<' '<<i<<' '<<j<<'\n';
}
}
cout<<dp[0][n - 1];
return 0;
}
