#include <bits/stdc++.h>
using namespace std;
int main()
{
    int N, M;
    cin >> N >> M;
    vector<int> V(N);
    for (int &v : V)
        cin >> v;
    vector<int> S(N);
    for (int i = 0; i < N; i++)
    {
        string s;
        cin >> s;
        for (int j = 0; j < M; j++)
            S[i] += (s[j] == 'o') << j;
    }

    vector<int> Z(1 << M);
    for (int i = 0; i < N; i++)
        Z[S[i]] += V[i];

    for (int i = 0; i < M; i++)
        for (int j = 0; j < (1 << M); ++j)
            if (j & (1 << i))
                Z[j] += Z[j - (1 << i)];

    vector<long> DP(1 << M);
    for (int i = 1; i < (1 << M); i++)
    {
        for (int j = 0; j < M; j++)
            if (i & (1 << j))
            {
                long v = Z[i - (1 << j)] - Z[i];
                DP[i] = max(DP[i], DP[i - (1 << j)] + v * v);
            }
    }

    cout << DP.back() << endl;
}