## https://yukicoder.me/problems/no/1288

import heapq

def main():
    N = int(input())
    S = input()
    V = list(map(int, input().split()))


    i_queue = []
    k_queue = []
    u_queue = []
    answer = 0
    for i in reversed(range(N)):
        s = S[i]
        if s == "i":
            heapq.heappush(i_queue, -V[i])
        elif s == "k":
            if len(i_queue) > 0:
                v = heapq.heappop(i_queue)
                v = -v
                heapq.heappush(k_queue, -(V[i] + v))
        elif s == "u":
            if len(k_queue) > 0:
                v = heapq.heappop(k_queue)
                v = -v
                heapq.heappush(u_queue, -(V[i] + v))
        else:
            if len(u_queue) > 0:
                v = heapq.heappop(u_queue)
                v = -v
                answer += v + V[i]
    print(answer)
            

if __name__ == "__main__":
    main()