mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    N = int(input())
    A = list(map(int, input().split()))
    S = input().rstrip('\n')

    nxt = [[-1] * 26 for _ in range(N + 1)]
    for i in range(N - 1, -1, -1):
        s = S[i]
        for j in range(26):
            nxt[i][j] = nxt[i + 1][j]
            if ord(s) - 97 == j:
                nxt[i][j] = i + 1

    dp0 = [0] * (N + 1)
    dp1 = [0] * (N + 1)
    dp0[0] = 1
    for i, s in enumerate(S):
        for c in range(26):
            j = nxt[i][c]
            if j == -1:
                continue
            a = A[j - 1]
            if i != 0:
                if ord(S[i - 1]) - 97 == c:
                    dp0[j] = (dp0[j] + (dp1[i] * (a - 1)) % mod) % mod
                    dp1[j] = (dp1[j] + dp1[i]) % mod
                else:
                    dp0[j] = (dp0[j] + ((dp0[i] + dp1[i]) * (a - 1)) % mod) % mod
                    dp1[j] = (dp1[j] + dp0[i] + dp1[i]) % mod
            else:
                dp0[j] = (dp0[j] + ((dp0[i] + dp1[i]) * (a - 1)) % mod)%mod
                dp1[j] = (dp1[j] + dp0[i] + dp1[i])%mod
    ans = 0
    for i in range(1, N + 1):
        ans = (ans + dp0[i])%mod
        ans = (ans + dp1[i])%mod
    print(ans)


if __name__ == '__main__':
    main()