# include <iostream>
# include <vector>
# include <algorithm>
# include <map>
# define int long long
using namespace std;
const long long INF=1e18;
const int MAX=2511;
int n;
long long A,B,C;
char a[MAX];
const long long mod[2]={(long long)1e9+7,(long long)1e9+9};
const long long K=31;
long long power[MAX][2];
void hesh_precalc()
{
power[0][0]=1;
power[0][1]=1;
for(int i=1;i<=n;i++)
{
power[i][0]=(power[i-1][0]*K)%mod[0];
power[i][1]=(power[i-1][1]*K)%mod[1];
}
}
struct hesh
{
int len=0;
long long h[2]={0,0};
bool friend operator == (hesh _A, hesh _B)
{
return _A.len==_B.len and _A.h[0]==_B.h[0] and _A.h[1]==_B.h[1];
}
bool friend operator < (hesh _A, hesh _B)
{
if(_A.len!=_B.len) return _A.len<_B.len;
if(_A.h[0]!=_B.h[0]) return _A.h[0]<_B.h[0];
return _A.h[1]<_B.h[1];
}
void add_back(int x)
{
h[0]=(h[0]*K+x)%mod[0];
h[1]=(h[1]*K+x)%mod[0];
len++;
}
void rem_front(int x)
{
len--;
h[0]=(h[0]-power[len][0]*x+mod[0]*x)%mod[0];
h[1]=(h[1]-power[len][1]*x+mod[1]*x)%mod[1];
}
};
int c[MAX];
int nxt[MAX][MAX];
long long dp[MAX][MAX];
int cnt[MAX];
vector<int> toAdd[MAX];
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n;
for(int i=1;i<=n;i++) cin>>a[i];
cin>>A>>B>>C;
hesh_precalc();
for(int k=1;k<=n;k++)
{
for(int i=1;i<=n;i++) nxt[i][k]=-1;
map<hesh,int> mp;
vector<vector<int>> v(n+1);
int diff=0;
hesh H;
for(int i=1;i<=k;i++) H.add_back(a[i]-'a'+1);
diff++;
mp[H]=diff;
c[1]=diff;
v[diff].push_back(1);
for(int i=2;i+k-1<=n;i++)
{
H.rem_front(a[i-1]-'a'+1);
H.add_back(a[i+k-1]-'a'+1);
if(mp.find(H)==mp.end())
{
diff++;
mp[H]=diff;
c[i]=diff;
}
else c[i]=mp[H];
v[c[i]].push_back(i);
}
for(int d=1;d<=diff;d++)
{
int sz=v[d].size(),ptr=0;
for(int i=0;i<sz;i++)
{
while(ptr+1<i and v[d][i]-v[d][ptr+1]>=k) ptr++;
if(v[d][i]-v[d][ptr]>=k) nxt[v[d][i]][k]=v[d][ptr];
}
}
//cout<<k<<":";
//for(int i=1;i<=n;i++) cout<<nxt[i][k]<<" ";
//cout<<"\n";
}
for(int r=1;r<=n;r++)
{
for(int l=1;l<=r;l++)
{
dp[l][r]=INF;
cnt[l]=0;
toAdd[l].clear();
}
long long mn=INF;
for(int l=r;l>=1;l--)
{
for(int k: toAdd[l])
{
cnt[k]++;
mn=min(mn,C*cnt[k]-A*(cnt[k]*k)+B+dp[r-k+1][r]);
if(nxt[l][k]!=-1) toAdd[nxt[l][k]].push_back(k);
}
dp[l][r]=min(dp[l][r],A*(r-l+1)+mn);
dp[l][r]=min(dp[l][r],dp[l][r-1]+A);
int k=r-l+1;
cnt[k]++;
mn=min(mn,C*cnt[k]-A*(cnt[k]*k)+B+dp[r-k+1][r]);
if(nxt[l][k]!=-1) toAdd[nxt[l][k]].push_back(k);
}
}
cout<<dp[1][n]<<"\n";
return 0;
}
