#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int DY4[]{1, 0, -1, 0}, DX4[]{0, -1, 0, 1};
constexpr int DY8[]{1, 1, 0, -1, -1, -1, 0, 1};
constexpr int DX8[]{0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U>
inline bool chmax(T& a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U>
inline bool chmin(T& a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

template <typename Ring>
std::vector<Ring> fast_zeta_transform(
    std::vector<Ring> a, const bool adds_superset, const Ring ID = 0,
    const std::function<Ring(const Ring&, const Ring&)> fn =
        [](const Ring& a, const Ring& b) -> Ring { return a + b; }) {
  int n = a.size(), p = 1;
  while ((1 << p) < n) ++p;
  n = 1 << p;
  a.resize(n, ID);
  if (adds_superset) {
    for (int i = 1; i < n; i <<= 1) {
      for (int s = 0; s < n; ++s) {
        if (s & i) continue;
        a[s] = fn(a[s], a[s | i]);
      }
    }
  } else {
    for (int i = 1; i < n; i <<= 1) {
      for (int s = 0; s < n; ++s) {
        if (s & i) continue;
        a[s | i] = fn(a[s | i], a[s]);
      }
    }
  }
  return a;
}

int main() {
  int n, m; cin >> n >> m;
  vector<int> v(n);
  REP(i, n) cin >> v[i];
  vector a(m, vector(1 << m, 0LL));
  REP(i, n) {
    string s; cin >> s;
    int x = 0;
    REP(j, m) {
      if (s[j] == 'x') x |= 1 << j;
    }
    REP(j, m) {
      if (s[j] == 'o') a[j][x] += v[i];
    }
  }
  REP(j, m) a[j] = fast_zeta_transform(a[j], true);
  vector<ll> dp(1 << m, 0);
  REP(i, 1 << m) REP(j, m) {
    if (i >> j & 1) continue;
    chmax(dp[i | (1 << j)], dp[i] + 1LL * a[j][i] * a[j][i]);
  }
  cout << dp[(1 << m) - 1] << '\n';
  return 0;
}