#include <bits/stdc++.h>
#define ll long long
#define ff first
#define ss second
using namespace std;
ll n,A,B,C;
string s="#";
string s1;
ll xar[2501];
ll hs[2501];
ll num[501];
ll pir[501];
ll dp[2501][2501];
ll p=1000000007;
void makehash(string s){
xar[0]=1;
ll cd;
for(int k=1;k<=n;k++){
xar[k]=xar[k-1]*31;
xar[k]%=p;
}
hs[0]=0;
for(int k=1;k<=n;k++){
hs[k]=hs[k-1]*31;
hs[k]%=p;
cd=s[k]-'a';
hs[k]+=cd;
hs[k]%=p;
}
}
ll gethash(int l,int r){
ll ans;
ll raodenoba=r-l+1;
ll r1=hs[r];
ll r2=hs[l-1]*xar[raodenoba];
r1%=p;
r2%=p;
ans=r2-r1;
ans+=p;
return ans;
}
int main(){
/*ios_base::sync_with_stdio(0);
cin.tie(0);*/
cin>>n;
cin>>s1;
s+=s1;
cin>>A>>B>>C;
for(int i=1;i<=n;i++){
for(int j=i;j<=n;j++){
dp[i][j]=1e18;
}
}
fill(pir,pir+n+1,1e18);
ll len=0;
ll newlen=0;
ll ric1=0,ric2=0;
makehash(s);
for(int r=1;r<=n;r++){
fill(pir,pir+r+1,1e18);
fill(num,num+r+1,0);
for(int l=r;l>=1;l--){
dp[l][r]=min(dp[l][r],dp[l][r-1]+A);
for(int i=l;i<=r;i++){
len=i-l+1;
ric1=gethash(l,i);
ric2=gethash(r-len+1,r);
if(ric1==ric2&&i<pir[len]){
pir[len]=l;
num[len]++;
}
newlen=(C-len*A)*num[len]+(r-l+1)*A+dp[r-len+1][r]+B;
dp[l][r]=min(dp[l][r],newlen);
}
}
}
cout<<dp[1][n];
return 0;
}
