#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <random>
#include <stdio.h>
#include <fstream>
#include <functional>
#include <cassert>
using namespace std;

#define rep(i,n,c) for (int i=0;i<n;i+=c)
#define append push_back
#define all(x) (x).begin(), (x).end()

template<class T>
using vec = vector<T>;
template<class T>
using vvec = vec<vec<T>>;
template<class T>
using vvvec = vec<vvec<T>>;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;


template<class T>
bool chmin(T &a, T b){
  if (a>b){
    a = b;
    return true;
  }
  return false;
}

template<class T>
bool chmax(T &a, T b){
  if (a<b){
    a = b;
    return true;
  }
  return false;
}

template<class T>
T sum(vec<T> x){
  T res=0;
  for (auto e:x){
    res += e;
  }
  return res;
}

template<class T>
void printv(vec<T> x){
  for (auto e:x){
    cout<<e<<" ";
  }
  cout<<"\n";
}

ll pow(ll n,ll k){
  ll res = 1;
  while (k){
    if (k&1){
      res *= n;
    }
    n *= n;
    k >>= 1;
  }
  return res;
}

int main(){
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);

  int N,M;
  cin>>N>>M;
  vec<ll> V(N);
  for (auto &v:V){
    cin>>v;
  }

  vec<ll> bit(1<<M,0);
  string S;
  int t;
  for (int i=0;i<N;i++){
    cin>>S;
    t = 0;
    for (int j=0;j<M;j++){
      if (S[j]=='o'){
        t += (1<<j);
      }
    }
    bit[t] += V[i];
  }

  auto calc = [bit](int free_group,int o_group){
    ll res = bit[o_group];
    int tmp = free_group;
    while (tmp){
      res += bit[tmp+o_group];
      tmp = (tmp-1) & free_group;
    }
    return res;
  };

  vec<ll> dp(1<<M,0);
  int ALL = (1<<M) - 1;
  ll score;
  for (int i=1;i<(1<<M);i++){
    for (int j=0;j<M;j++){
      t = (1<<j);
      if ((i>>j) & 1){
        score = calc(i-t,t);
        chmax(dp[i],dp[i-t]+score*score);
      }
    }
  }

  cout<<dp[ALL]<<endl;
}