MOD = 10 ** 9 + 7
n = int(input())
a = [0] + list(map(int, input().split())) + [0]
s = [26] + [ord(c) - 97 for c in input()]
d = [[n + 1] * (n + 1) for _ in range(26)]
for i in range(n - 1, -1, -1):
    for j in range(26):
        if s[i + 1] == j:
            d[j][i] = i + 1
        else:
            d[j][i] = d[j][i + 1]
dp1 = [0] * (n + 2)
dp2 = [0] * (n + 2)
dp1[0] = 1
for i in range(n):
    dp1[i] %= MOD
    dp2[i] %= MOD
    for j in range(26):
        if s[i] == j:
            dp1[d[j][i]] += dp1[i]
            dp2[d[j][i]] += dp1[i] * (a[d[j][i]] - 1)
        else:
            dp1[d[j][i]] += (dp1[i] + dp2[i])
            dp2[d[j][i]] += (dp1[i] + dp2[i]) * (a[d[j][i]] - 1)
print((sum(dp1[1:-1]) + sum(dp2[1:-1])) % MOD)