#include<bits/stdc++.h>
using namespace std;
const int nax = 2503;
const long long INF = 1e18;
const int P = 31;
const int M = 1e9 + 11;
int n;
string s;
long long A, B, C;
long long dp[nax][nax];
long long hv[nax];
long long pw[nax];
int nxt[nax];
int get(int l, int r) {
long long ret = hv[r] - hv[l-1];
if(ret<0) ret += M;
ret = (ret * pw[n-r]) % M;
return ret;
}
void PlayGround() {
cin>>n>>s>>A>>B>>C;
s = '@' + s;
pw[0] = 1;
for(int i=1; i<=n; ++i) {
pw[i] = (pw[i-1] * P) % M;
hv[i] = (pw[i] * (s[i]-'a'+1)) + hv[i-1];
hv[i] %= M;
}
for(int i=1; i<=n; ++i) {
for(int j=1; j<=n; ++j) {
dp[i][j] = INF;
}
dp[i][i] = A;
}
for(int un=1; un<=n; ++un) {
memset(nxt, -1, sizeof nxt);
unordered_map<int, deque<int>>app;
for(int i=1; i+un-1<=n; ++i) if(un>1) {
dp[i][i+un-1] = min(dp[i][i+un-1], min(dp[i+1][i+un-1], dp[i][i+un-2]) + A);
}
for(int i=n-un+1; i>0; --i) {
int crval = get(i, i+un-1);
auto &v = app[crval];
v.push_back(i);
while(v.size()>=2 && v[1]>i+un-1)
v.pop_front();
if(v[0]<=i+un-1) nxt[i] = -1;
else nxt[i] = v[0];
}
for(int i=1; i<=n; ++i) {
for(int j=nxt[i], cnt=2; j!=-1; j=nxt[j], ++cnt) {
dp[i][j+un-1] = min(dp[i][j+un-1],
dp[i][i+un-1]+B+cnt*C + (j+un-1-i+1 - cnt*un) * A);
}
}
}
cout<<dp[1][n]<<'\n';
// cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
PlayGround();
return 0;
}
