#include <bits/stdc++.h>
#define int long long
using namespace std;
const int base = 101LL;
const int mod = 1e9 + 7;
int n,a,b,c;
string s;
const int maxn = 2510;
int dp[maxn][maxn];
int h[maxn],p[maxn];
inline int get(int l, int r)
{
return (h[r]-(h[l-1]*p[r-l+1]%mod)+mod)%mod;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
cin>>n;
cin>>s;
cin>>a>>b>>c;
p[0]=1LL;
for (int i=1; i<=n; i++) p[i]=p[i-1]*base%mod;
h[0]=0LL;
for (int i=1; i<=n; i++) h[i]=(h[i-1]*base%mod + (s[i-1]-'a'+1))%mod;
for (int i=1; i<=n; i++)
for (int j=i; j<=n; j++) dp[i][j] = a*(j-i+1);
for (int len=1; len<n; len++)
for (int j=len; j<=n; j++)
{
int i=j-len+1;
int num = 1; int r = i-1;
for (int z=i-1; z>=1; z--)
{
if (r-z+1>=len)
{
if (get(z,z+len-1) == get(i,j))
{
num++;
r=z-1;
}
}
dp[z][j]=min(dp[z][j],dp[i][j]+b+num*c+(j-z+1-(num*len))*a);
dp[z][j]=min(dp[z][j],dp[i][j]+(i-z)*a);
}
num=1;
int l=j+1;
for (int z=j+1; z<=n; z++)
{
if (z-l+1>=len)
{
if (get(z-len+1,z) == get(i,j))
{
num++;
l=z+1;
}
}
dp[i][z]=min(dp[i][z],dp[i][j]+b+num*c+(z-i+1-(num*len))*a);
dp[i][z]=min(dp[i][z],dp[i][j]+(z-j)*a);
}
// cout<<i<<' '<<j<<" := "<<dp[i][j]<<'\n';
}
cout<<dp[1][n]<<'\n';
}
