#include<bits/stdc++.h>
#define ll long long
#define F first
#define S second
#define in insert
#define pb push_back
#define ppb pop_back()
#define d3 ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define cans cout << ans << "\n";
#define yes cout << "Yes" << "\n";
#define no cout << "No" << "\n";
#define pll pair<ll,ll>
#define lin cout << "\n";
#define sqr 340
#define mod 1000000007
#define mid ((l+r)/2)
#define lc (2*x)
#define rc (2*x+1)
using namespace std;
ll n;
string s;
ll A , B , C;
bool e[209][209][209][209];
ll dp[209][209];
ll solve(ll l , ll r)
{
if(dp[l][r])
return dp[l][r];
ll ans = (r-l+1)*A;
for(ll i = l ; r>i ; i++)
{
for(ll j = i ; r>j ; j++)
{
ll ans1 = solve(i,j) + B + (i-l)*A + C;
for(ll h = j+1 ; r>=h ; h++)
{
ll i1 = h , j1 = h+j-i;
if(e[i][j][i1][j1])
{
ans1+=C;
h=j1;
}
else
ans1+=A;
}
ans=min(ans,ans1);
}
}
dp[l][r]=ans;
return ans;
}
int main()
{
d3
cin >> n;
cin >> s;
cin >> A >> B >> C;
for(ll i = 0 ; n>i ; i++)
{
for(ll j = i ; n>j ; j++)
{
for(ll i1 = j+1 ; n>i1 ; i1++)
{
ll j1 = i1+(j-i);
e[i][j][i1][j1]=1;
for(ll h = i ; j>=h ; h++)
{
if(s[h]!=s[i1+(h-i)])
e[i][j][i1][j1]=0;
}
}
}
}
cout << solve(0,n-1);
}
