import sys
from operator import itemgetter
from collections import defaultdict, deque
from heapq import heapify, heappop, heappush
from bisect import bisect_left, bisect_right
import math
import itertools
import copy

stdin=sys.stdin
sys.setrecursionlimit(10 ** 8)

ip=lambda: int(sp())
fp=lambda: float(sp())
lp=lambda:list(map(int,stdin.readline().split()))
sp=lambda:stdin.readline().rstrip()
Yp=lambda:print('Yes')
Np=lambda:print('No')
inf = 1 << 60
inf = float('inf')
mod = 10 ** 9 + 7
#mod = 998244353
eps = 1e-9
sortkey1 = itemgetter(0)
sortkey2 = lambda x: (x[0], x[1])

###############################################################

N = ip()
A = lp()
A = [0] + A + [0]
S = list(sp())
S = ['a'] + S
digits = [[N + 1 for _ in range(26)] for _ in range(N + 1)]
for i in range(N - 1, -1, -1):
    now = ord(S[i + 1]) - ord('a')
    for j in range(26):
        digits[i][j] = digits[i + 1][j]
        if now == j:
            digits[i][j] = i + 1

## dp1 == i文字目がAi個あったときに全部使う時パターン
dp1 = [0 for _ in range(N + 2)]
## dp2 == i文字目がAi個あったときに全部使う時パターン以外
dp2 = [0 for _ in range(N + 2)]
dp1[0] = 1

for i in range(N):
    now = ord(S[i]) - ord('a')
    for j in range(26):
        if now == j:
            dp1[digits[i][j]] += dp1[i]
            dp2[digits[i][j]] += dp1[i] * (A[digits[i][j]] - 1)
        else:
            dp1[digits[i][j]] += dp1[i] + dp2[i]
            dp2[digits[i][j]] += (dp1[i] + dp2[i]) * (A[digits[i][j]] - 1)
        dp1[digits[i][j]] %= mod
        dp2[digits[i][j]] %= mod

ans = 0
for i in range(1, N + 2):
    ans += dp1[i] + dp2[i]
    ans %= mod

print(ans)