DP

#include<bits/stdc++.h>
using namespace std;
using ll = long long;

const ll N = 1e5 + 10;
ll n;
ll a[N], dp[N];
string s;

int main() {
    cin >> n >> s;
    s = " " + s;  // 下标从1开始
    
    for (ll i = 1; i <= n; i++) {
        cin >> a[i];
    }
    
    // dp[i]：前 i 个字符划分的最大价值
    dp[0] = 0;
    
    for (ll i = 1; i <= n; i++) {
        dp[i] = -1e18;
        ll mask = 0;  // 位运算记录出现过的字母
        
        // 从 i 向左扩展，找所有合法子串 s[j..i]
        for (ll j = i; j >= 1; j--) {
            ll bit = 1 << (s[j] - 'a');
            if (mask & bit) break;  // 字母重复，停止扩展
            
            mask |= bit;
            ll len = i - j + 1;
            dp[i] = max(dp[i], dp[j - 1] + a[len]);
        }
    }
    
    cout << dp[n] << endl;
    return 0;
}