import sys,random,bisect
from collections import deque,defaultdict
from heapq import heapify,heappop,heappush
from itertools import permutations
from math import log,gcd

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

mod = 10**9 + 7

N = int(input())
A = li()
S = input()
S = [ord(s)-ord("a") for s in S]

dp = [0 for i in range(N)]
memo = [0 for i in range(26)]
for i in range(N):
    dp[i] = A[i]
    for j in range(26):
        if j!=S[i]:
            dp[i] += A[i] * memo[j]
        else:
            dp[i] += memo[j]
        dp[i] %= mod
    dp[i] %= mod
    memo[S[i]] = dp[i]

res = sum(memo) % mod
print(res)