import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

m = 26
mod = 10 ** 9 + 7
n = ni()
a = [1] + na()
s = [ord(x)-97 for x in input()]

f = [[-1 for i in range(n+1)] for j in range(m)]

for i in range(n-1, -1, -1):
    for j in range(m):
        f[j][i] = f[j][i+1]
    f[s[i]][i] = i
s = [-1] + s
# print(f)

dp = [0] * (n + 1)
dp[0] = 1

for i in range(n):
    for j in range(m):
        if f[j][i] != -1:
            if s[i] != j:
                dp[f[j][i] + 1] += dp[i] * a[i] % mod
            else:
                dp[f[j][i] + 1] += dp[i]
            
            dp[f[j][i] + 1] %= mod
# print(dp)
ans = 0
for i in range(1, n + 1):
    ans += dp[i] * a[i] % mod
    ans %= mod

print(ans)