#include <bits/stdc++.h>
#define int ll
using namespace std;
#define ll long long
#define f first
#define s second
#define pii pair<ll, ll>
#define SZ(x) (int)(x).size()
#define ALL(x) (x).begin(), (x).end()
#define pb push_back
#define MX(a,b) a = max(a,b)
#define MN(a,b) a = min(a,b)
#define FOR(i,a,b) for (int i = a; i<b; ++i)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n+1)
#define RREP(i,n) for (int i = n-1; i>=0; --i)
#ifdef BALBIT
#define bug(...) cerr<<"#"<<__LINE__<<"- "<<#__VA_ARGS__<<": ", _do(__VA_ARGS__)
template<typename T> void _do(T && x) {cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T && x, S && ...y) {cerr<<x<<", "; _do(y...);}
#else
#define bug(...)
#define endl '\n'
#endif // BALBIT
const int maxn = 2500+5;
int comlen[maxn][maxn];
string s;
int A,B,C; // single letter, cut, paste
int dp[maxn][maxn];
vector<int> todo[maxn];
int nxt[maxn][maxn]; // starting at i, with length j
signed main(){
ios::sync_with_stdio(0), cin.tie(0);
int n; cin>>n;
cin>>s;
cin>>A>>B>>C;
// build comlen
for (int j = n-1; j>=0; --j) {
for (int i = j; i>=0; --i) {
if (s[i] != s[j]) {comlen[i][j] = comlen[j][i] = 0;}
else{
comlen[i][j] = comlen[j][i] = 1 + comlen[i+1][j+1];
}
}
}
REP(i,n) REP(j,i) bug(i,j,comlen[i][j]);
memset(nxt, -1, sizeof nxt);
REP(i,n) {
set<int> have;
vector<pii> yom;
for (int j = i+1; j<n; ++j) {
yom.pb({comlen[i][j], j});
}
sort(ALL(yom), greater<pii>());
int at = 0;
for (int len = n; len>=1; --len) {
if (i + len*2 <=n) {
while (at < SZ(yom) && yom[at].f >= len) {
have.insert(yom[at].s); ++at;
}
auto it = have.lower_bound(i+len);
nxt[i][len] = it==have.end()?-1 : *it;
bug(nxt[i][len]);
}
}
}
RREP(i,n) {
REP(j,n) todo[j].clear();
for (int len = 1; len*2+i<=n; ++len) {
int at = nxt[i][len];
while(at != -1) {
todo[at + len-1].pb(len);
at = nxt[at][len];
}
}
vector<int> howgood(n+1);
int best = 0;
for (int j = i; j<n; ++j) {
int len = j-i+1;
dp[i][j] = A + dp[i+1][j];
for (int t : todo[j]) {
howgood[t] += -t * A + C;
MN(best, howgood[t]);
}
bug(best);
MN(dp[i][j], len * A + best);
howgood[len] = dp[i][j] + B - (len) * A + C;
MN(best, howgood[len]);
}
}
cout<<dp[0][n-1]<<endl;
}
