#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;
const int N = 2550;
int pre[N][N];
vector<pii> wright[N][N];
ll dp[N][N];
ll A, B, C;
char s[N];
int n;
// TODO: use kmp, this is probably O(n^3) (but with glibc's blazingly fast mem* ans str*)
void make_pre()
{
memset(pre, -1, sizeof(pre));
Loop (r2,1,n+1) {
int len = 1;
LoopR (r1,len,r2) {
if (r2-r1 < len)
continue;
if (memcmp(&s[r2-len], &s[r1-len], len) == 0) {
pre[r2-len][r2] = r1-len;
++len;
++r1;
}
}
}
}
void make_wright()
{
Loop (l,0,n) Loop (r,l+1,n+1) {
int k = 1;
int p = l;
do {
wright[p][r].push_back({r-l, k});
p = pre[p][p+r-l];
++k;
} while (p != -1);
}
}
void calc_dp()
{
Loop (r,1,n+1) LoopR (l,0,r) {
dp[l][r] = min(dp[l][r-1], dp[l+1][r]) + A;
for (auto [k, cnt] : wright[l][r])
dp[l][r] = min(dp[l][r], dp[l][l+k] + B + C * cnt + A * (r-l - cnt*k));
}
}
int main()
{
cin.tie(0) -> sync_with_stdio(false);
cin >> n >> s >> A >> B >> C;
make_pre();
make_wright();
calc_dp();
cout << dp[0][n] << '\n';
}
