from bisect import bisect_left
def ch(s):
    return ord(s) - ord('a')
N = int(input())
memo = [[] for _ in range(26)]
A = list(map(int,input().split()))
mod = 10 ** 9 + 7
S = list(map(ch,list(input())))
dp = [0 for _ in range(N)]
for i in range(N):
    if memo[S[i]] == []:
        dp[i] = 1
    memo[S[i]].append(i)
for i in range(N):
    for k in range(26):
        if memo[k] == []:
            pass
        else:
            index = bisect_left(memo[k],i+1)
            if index == len(memo[k]):
                continue
            nx = memo[k][index]
            if S[i] == k:
                dp[nx] += dp[i]
            else:
                dp[nx] += dp[i] * A[i]
            dp[nx] %= mod
ans = 0
for i in range(N):
    ans += dp[i] * A[i]
    ans %= mod
print(ans)