import sys
input = lambda : sys.stdin.readline().rstrip()

write = lambda x: sys.stdout.write(x+"\n")
debug = lambda x: sys.stderr.write(x+"\n")
writef = lambda x: print("{:.12f}".format(x))


def zeta_sub(val, n):
    """
    given: そのbitの出席パターン回数
    compute: 各bitのsubsetについて、countの総和
    """
    # len(val)==2^n
    out = val[:]
    for i in range(n):
        for j in range(1<<n):
            if j>>i&1:
                out[j] += out[j^(1<<i)]
    return out

n,m = list(map(int, input().split()))
assert 1<=n<=10**5 and 1<=m<=20
vs = list(map(int, input().split()))
assert len(vs)==n
vals = [0]*(1<<m)
for i in range(n):
    assert 1<=vs[i]<=10**4
    s = input()
    assert len(s)==m and "o" in s
    b = int(s.replace("o", "1").replace("x", "0")[::-1], 2)
    vals[b] += vs[i]
size = zeta_sub(vals, m)
dp = [0]*(1<<m)
for b in range(1<<m):
    val = dp[b]
    for i in range(m):
        if b>>i&1:
            continue
        nb = b|(1<<i)
        dp[nb] = max(dp[nb], val + (size[nb] - size[b])**2)
ans = dp[(1<<m)-1]
print(ans)