N = int(input())
A = list(map(int,input().split()))
S = input()
last = [-1] * 26
P = 10 ** 9 + 7
dp = [0] * N
_sum = [0] * (N+1)
dp[0] = A[0]
c = ord(S[0]) - ord('a')
last[c] = 0
_sum[1] = A[0]
hoka = [0] * N
hoka[0] = 1
for i in range(1,N):
    c = ord(S[i]) - ord('a')
    if last[c] == -1:
        dp[i] = (_sum[i]+1) * A[i] % P
        hoka[i] = _sum[i]+1
    else:
        dp[i] = (_sum[i] - _sum[last[c]+1] + hoka[last[c]] ) * A[i] % P
        hoka[i] = (_sum[i] - _sum[last[c]+1] + hoka[last[c]]) % P
    _sum[i+1] = (_sum[i] + dp[i]) % P
    last[c] = i
ans = 0
for i in range(N):
    ans = (ans + dp[i]) % P
print(ans)