mod = 10 ** 9 + 7


N = int(input())
A = list(map(int, input().split()))
S = [ord(s) - 97 for s in input()]
pos = [[] for _ in range(26)]
for i in reversed(range(N)):
    pos[S[i]].append(i)

dp = [0] * N
for i in range(26):
    if pos[i]:
        dp[pos[i][-1]] = 1

for i, s in enumerate(S):
    pos[s].pop()
    for j in range(26):
        if pos[j] and s != j:
            dp[pos[j][-1]] += dp[i] * A[i]
            dp[pos[j][-1]] %= mod
        if pos[j] and s == j:
            dp[pos[j][-1]] += dp[i]
            dp[pos[j][-1]] %= mod


ans = 0
for i in range(N):
    ans += A[i] * dp[i]
    ans %= mod
print(ans)