#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>

using namespace std;
using namespace __gnu_pbds;
typedef long long ll;

const ll N = 2500 + 5;
const ll S1 = 114, S2 = 514, M1 = 998244353, M2 = 1e9 + 7;

inline void checkmin(ll &x, ll y){
	if(y < x) x = y;
}

class Hash{
public:
	ll x1, x2;
	inline Hash(){
		x1 = x2 = 0;
	}
};

inline bool operator < (Hash H1, Hash H2){
	if(H1.x1 != H2.x1) return H1.x1 < H2.x1;
	else return H1.x2 < H2.x2;
}

inline Hash operator + (Hash H, char x){
	H.x1 = (H.x1 * S1 + x) % M1;
	H.x2 = (H.x2 * S2 + x) % M2;
	return H;
}

ll n = 0, a = 0, b = 0, c = 0, f[N][N] = {}, g[N][N] = {};
cc_hash_table<ll, vector<ll> > M[N] = {};
char str[N] = {};

int main(){
	scanf("%lld %s %lld %lld %lld", &n, str + 1, &a, &b, &c);
	for(ll r = 1 ; r <= n ; r ++){
		Hash H = Hash();
		for(ll l = r ; l >= 1 ; l --){
			H = H + str[l];
			M[r - l + 1][H.x1 * M2 + H.x2].push_back(r);
		}
	}
	for(ll x = 1 ; x <= n ; x ++) for(auto P : M[x]){
		vector<ll> pos = P.second;
		for(ll i : pos){
			auto it = lower_bound(pos.begin(), pos.end(), i + x);
			if(it != pos.end()) g[x][i] = *it;
		}
	}
	memset(f, 0x3f, sizeof(f));
	for(ll l = n ; l >= 1 ; l --) for(ll r = l ; r <= n ; r ++){
		if(l == r) checkmin(f[l][r], a);
		else checkmin(f[l][r], min(f[l + 1][r], f[l][r - 1]) + a);
		for(ll x = r - l + 1, d = 1, i = r ; i ; i = g[x][i], d ++) checkmin(f[l][i], f[l][r] + a * (i - l + 1 - d * x) + b + c * d);
	}
	printf("%lld", f[1][n]);
	return 0;
}