#include "bits/stdc++.h"
using namespace std;
#define ff first
#define ss second
#define all(v) v.begin(), v.end()
#define ll long long
#define pb push_back
#define pii pair<int, int>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define tr(i, c) for(auto i = c.begin(); i != c.end(); ++i)
#define wr puts("----------------")
#define mm make_pair
template<class T>bool umin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool umax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
const int N = 2505;
const int md = 1e9+7;
const int B = 77777;
const ll inf = 1e18;
int n, a, b, c, pw[N], dv[N], pr[N];
ll dp[N][N];
char s[N];
int mul(int x, int y){
return 1LL*x*y%md;
}
int ad(int x, int y){
return x+y>=md?x+y-md:x+y;
}
int sb(int x, int y){
return x-y<0?x-y+md:x-y;
}
int qp(int x, int k){
int r=1;
while(k){
if(k&1)
r=mul(r, x);
x=mul(x, x);
k>>=1;
}
return r;
}
int gH(int l, int r){
return mul(sb(pr[r], pr[l-1]), dv[l]);
}
int main(){
scanf("%d", &n);
scanf("%s", s+1);
scanf("%d%d%d", &a, &b, &c);
pw[0]=1;
for(int i = 1; i <= n; ++i)
pw[i]=mul(pw[i-1], B);
dv[n]=qp(pw[n], md-2);
for(int i = n-1; i >= 0; --i)
dv[i]=mul(dv[i+1], B);
for(int i = 1; i <= n; ++i)
pr[i]=ad(pr[i-1], mul(pw[i], s[i]-'a'));
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
dp[i][j]=inf;
for(int l = 0; l < n; ++l){
vector<int> to(n+1, -1);
map<int, int> mp;
for(int i = n-l; i >= 1; --i){
int j=i+l;
if(j+1+l<=n)
mp[gH(j+1, j+1+l)]=j+1;
int h=gH(i, j);
if(mp.count(h))
to[i]=mp[h];
if(i==j)
dp[i][j]=a;
else
umin(dp[i][j], min(dp[i+1][j], dp[i][j-1])+a);
int x=i, ct=1;
while(to[x]!=-1){
x=to[x], ct++;
umin(dp[i][x+l], dp[i][j]+b+1LL*c*ct+1LL*a*((x+l-i+1)-ct*(l+1)));
}
}
}
printf("%lld\n", dp[1][n]);
return 0;
}
