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

from atcoder.mincostflow import MCFGraph

MAXINT = 10 ** 14

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

    # ネットワークフローを使って解く
    mcf_graph = MCFGraph(2 * N + 2)

    for i in range(N):
        if S[i] == "y":
            mcf_graph.add_edge(0, i + 1, 1, 0)

    for i in range(N):
        if S[i] == "u":
            for j in range(i):
                if S[j] == "y":
                    mcf_graph.add_edge(N + j + 1, i + 1, 1, 0)
        elif S[i] == "k":
            for j in range(i):
                if S[j] == "u":
                    mcf_graph.add_edge(N + j + 1, i + 1, 1, 0)
        elif S[i] == "i":
            for j in range(i):
                if S[j] == "k":
                    mcf_graph.add_edge(N + j + 1, i + 1, 1, 0)
    
    for i in range(N):
        if S[i] == "i":
            mcf_graph.add_edge(N + i + 1, 2 * N + 1, 1, 0)

    for i in range(N):
        mcf_graph.add_edge(i + 1, N + i + 1, 1, MAXINT - V[i])
    
    s_list = mcf_graph.slope(0,  2 * N + 1)
    answer = 0
    for f, a in s_list:
        x = f * 4 * MAXINT - a
        answer = max(answer, x)
    print(answer)





        









    





                





    
        















if __name__ == "__main__":
    main()