import sys

# sys.setrecursionlimit(1000005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 63)
md = 10**9+7
# md = 998244353

n = II()
aa = LI()
cc = [ord(c)-97 for c in SI()]
nxt = [[-1]*26 for _ in range(n)]
for i in range(n-1)[::-1]:
    nxt[i] = nxt[i+1][:]
    nxt[i][cc[i+1]] = i+1
# p2D(nxt)

ans = 0
dp = [0]*n
first = [1]*26
for i, c in enumerate(cc):
    pre = dp[i]
    if first[c]:
        pre += 1
        first[c] = 0
    ans += pre*aa[i]%md
    ans %= md
    for nc in range(26):
        if nxt[i][nc] == -1: continue
        j = nxt[i][nc]
        if c == nc:
            dp[j] += pre
        else:
            dp[j] += pre*aa[i]%md
        dp[j] %= md

print(ans)