#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
	int N, M;cin >> N >> M;
	vector<ll> G((1 << M), 0);
	vector<ll> V(N, 0);ll sm = 0;
	for (int i = 0;i < N;i++) {
		cin >> V[i];
		sm += V[i];
	}
	vector<vector<ll>> zeta((1 << M), vector<ll>(M + 1, 0));
	for (int i= 0;i < N;i++) {
		string s;cin >> s;
		int bit = 0;
		for (int j = 0;j < M;j++) if (s[j] == 'x') bit |= (1 << j);
		G[bit] += V[i];
		zeta[bit][0] += V[i];
	}
	for (int i = 0;i < M;i++) for (int bit = 0;bit < (1 << M);bit++) {
		if (bit & (1 << i)) {
			zeta[bit][i + 1] = zeta[bit][i];
		} else {
			zeta[bit][i + 1] =zeta[bit][i] + zeta[bit | (1 << i)][i];
		}
	}
	vector<ll> S((1 << M), 0);
	for (int bit = 0;bit < (1 << M);bit++) S[bit] = sm - zeta[bit][M];
	vector<ll> dp(1 << M, 0);
	vector<vector<int>> bits(M + 1);
	for (int bit = 0;bit < (1 << M);bit++) bits[__builtin_popcount(bit)].push_back(bit);
	for (int k = 1;k <= M;k++) for (auto bit : bits[k]) {
		for (int v = 0;v < M;v++) {
			if (!(bit & (1 << v))) continue;
			ll t = S[bit] - S[bit ^ (1 << v)];
			dp[bit] = max(dp[bit], dp[bit ^ (1 << v)] + (t * t));
		}
	}
	cout << dp.back() << endl;
}