#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 2500+5;
const int mod = 1e9+7;
int p = 59;
int dp[N][N];
int pre[N];
int n, A, B, C;
string s;
int powmod(int x, int y){
if(!y) return 1;
int res = powmod(x, y/2);
if(y%2) return res * res % mod * x % mod;
return res * res % mod;
}
int get_hash(int l, int r){
return ((pre[r] - pre[l-1])%mod+mod)%mod * powmod(powmod(p, l-1), mod-2)%mod;
}
// for(int i=1; i<=n; i++)
void solve(){
cin >> n >> s >> A >> B >> C;
s = '%' + s;
for(int i=1; i<=n; i++) pre[i] = (pre[i-1]+(s[i]-'a'+1)*powmod(p, i)%mod)%mod;
for(int sz=0; sz<=n+1; sz++) for(int i=0; i<=n+1; i++) dp[sz][i] = 1e18;
for(int sz=1; sz<=n; sz++) dp[sz][sz] = A;
for(int sz=1; sz<=n; sz++){
vector<int> nxt(n+1, -1);
map<int, vector<int>> mp;
for(int i=1; i+sz-1<=n; i++) {
mp[get_hash(i, i+sz-1)].push_back(i);
}
for(int i=1; i+sz-1<=n; i++) {
int hash = get_hash(i, i+sz-1);
auto it = lower_bound(mp[hash].begin(), mp[hash].end(), i+sz);
if(it == mp[hash].end()) nxt[i] = -1;
else nxt[i] = *it;
}
for(int l=1; l+sz-1<=n; l++){
int r = l + sz - 1;
dp[l][r] = min(dp[l][r], min(dp[l][r-1], dp[l+1][r]) + A);
if(nxt[l] == -1) continue;
int you = dp[l][r] + B + C;
int p = nxt[l];
int end = r;
while(p != -1 and end <= n){
you += (p - end - 1)*A + C;
end = p + sz - 1;
dp[l][end] = min(dp[l][end], you);
p = nxt[p];
}
}
}
cout << dp[1][n];
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
solve();
}
