// oooo
/*
har chi delet mikhad bebar ~
gitar o ba khodet nabar! ~
;Amoo_Hasan;
*/
#include<bits/stdc++.h>
//#pragma GCC optimize("O3,no-stack-protector,unroll-loops")
//#pragma GCC target("avx2,fma")
using namespace std;
typedef long long ll;
typedef long double ld;
#define Sz(x) int((x).size())
#define All(x) (x).begin(), (x).end()
#define wtf(x) cout<<#x <<" : " <<x <<endl
constexpr ll inf = 1e18, N = 1e3 + 10, pr = 1000696969, mod = 1e9 + 9;
ll ha[N][N];
ll dp[N][N];
int main() {
ios :: sync_with_stdio(0), cin.tie(0);
int n; cin >>n;
string s; cin >>s;
ll A, B, C; cin >>A >>B >>C;
for(int i = 0; i < n; i++) dp[i][i] = A;
for(int i = 0; i < n; i++) ha[i][0] = (s[i] - 'a');
for(int len = 1; len < n; len++)
for(int i = 0; i < n - len; i++)
ha[i][len] = (ha[i][len - 1] * pr + (s[i + len] - 'a')) % mod;
for(int len = 1; len < n; len++) {
for(int i = 0; i < n - len; i++) {
int j = i + len;
dp[i][j] = dp[i][j - 1] + A;
for(int k = j; k > i; k--) {
int nu = j - k;
ll cnt = dp[k][j] + B, val = ha[k][nu], sum = cnt + C;
for(int x = i; x < k;) {
if(x + nu >= k || ha[x][nu] != val) {
x++;
sum += A;
}
else {
x += nu + 1;
sum += C;
}
}
dp[i][j] = min(dp[i][j], sum);
}
}
}
cout<<dp[0][n - 1];
return 0;
}
