import sys # sys.setrecursionlimit(200005) # sys.set_int_max_str_digits(200005) int1 = lambda x: int(x)-1 pDB = lambda *x: print(*x, end="\n", file=sys.stderr) p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr) def II(): return int(sys.stdin.readline()) def LI(): return list(map(int, sys.stdin.readline().split())) def LLI(rows_number): return [LI() for _ in range(rows_number)] def LI1(): return list(map(int1, sys.stdin.readline().split())) def LLI1(rows_number): return [LI1() for _ in range(rows_number)] def SI(): return sys.stdin.readline().rstrip() dij = [(0, 1), (-1, 0), (0, -1), (1, 0)] # dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)] # inf = -1-(-1 << 31) inf = -1-(-1 << 63) # md = 10**9+7 md = 998244353 from heapq import * class MinCostFlow: def __init__(self, n): self.inf = inf self.n = n self.to = [[] for _ in range(n)] def add_edge(self, u, v, cap, cost): self.to[u].append([v, cap, cost, len(self.to[v])]) self.to[v].append([u, 0, -cost, len(self.to[u])-1]) # s...source,t...sink,f...flow # これが本体 def cal(self, s, t, f): min_cost = 0 n = self.n pot = [0]*n while f: dist = [self.inf]*n pre_u = [-1]*n # 最短距離の遷移元の頂点 pre_e = [-1]*n # 最短距離の遷移元の辺 # ダイクストラで最短距離を求める hp = [] heappush(hp, (0, s)) dist[s] = 0 while hp: d, u = heappop(hp) if d > dist[u]: continue for i, (v, cap, cost, rev) in enumerate(self.to[u]): if cap == 0: continue nd = dist[u]+cost+pot[u]-pot[v] if nd >= dist[v]: continue dist[v] = nd pre_u[v] = u pre_e[v] = i heappush(hp, (nd, v)) # sinkまで届かなかったら不可能ということ if dist[t] == self.inf: return -1 # ポテンシャルを更新する for u in range(n): pot[u] += dist[u] # パスs-t上で最小の容量=流す量を求める u = t min_cap = f while u != s: u, e = pre_u[u], pre_e[u] min_cap = min(min_cap, self.to[u][e][1]) # フローから流す量を減らし、コストを加える f -= min_cap min_cost += min_cap*pot[t] # パスs-tの容量を更新する u = t while u != s: u, e, v = pre_u[u], pre_e[u], u self.to[u][e][1] -= min_cap rev = self.to[u][e][3] self.to[v][rev][1] += min_cap return min_cost n = II() S = ["yuki".find(c) for c in SI()] vv = LI() mf = MinCostFlow(n+2) s = n t = s+1 ii = [[], [], [], []] for i in range(n)[::-1]: c = S[i] if c == 3: mf.add_edge(i, t, 1, -vv[i]) elif ii[c+1]: mf.add_edge(i, ii[c+1][-1], 1, -vv[i]) ii[c].append(i) for c in range(4): for i, j in zip(ii[c], ii[c][1:]): mf.add_edge(j, i, n, 0) if ii[0]: mf.add_edge(s, ii[0][-1], n, 0) mf.add_edge(s, t, n, 0) ans = mf.cal(s, t, min(len(ii[c]) for c in range(4))) print(-ans)