#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={1,0,-1,0,1,1,-1,-1};
const ll dx[8]={0,1,0,-1,1,-1,1,-1};
template <typename T> inline bool chmax(T &a, T b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
  return ((a > b) ? (a = b, true) : (false));
}

int main(){
  ll n,m;cin >> n >> m;
  vl v(n);rep(i,n)cin >> v[i];
  vl bs(n);
  rep(i,n){
    string s;cin >> s;
    rep(j,m){
      bs[i]<<=1;
      if(s[j]=='o')bs[i]++;
    }
  }
  vvl subdp(m,vl(1<<m));
  ll mask=1<<m;mask--;
  rep(d,m){
    vl use;
    rep(i,n){
      if(!(bs[i]>>d&1))continue;
      use.emplace_back(i);
    }
    vl sdp(1<<m);
    for(auto p:use)sdp[bs[p]]+=v[p];
    rep(t,m){
      rep(bit,1<<m){
        if(bit>>t&1)sdp[bit]+=sdp[bit^(1<<t)];
      }
    }
    //rep(bit,1<<m)cout <<sdp[bit] <<" ";cout << endl;
    swap(subdp[d],sdp);
  }
  vl dp(1<<m);
  rep(bit,1<<m){
    /*vl use;
    rep(i,n){
      if(bs[i]&bit)continue;
      use.emplace_back(i);
    }*/
    rep(i,m){
      if(bit>>i&1)continue;
      /*ll val=0;
      for(auto p:use){
        if(bs[p]>>i&1)val+=v[p];
      }*/
      chmax(dp[bit|(1<<i)],dp[bit]+subdp[i][bit^mask]*subdp[i][bit^mask]);
    }
  }
  cout << dp.back() << endl;

}