#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

template<typename T>
vector<vector<T>> vec2d(int n, int m, T v){
    return vector<vector<T>>(n, vector<T>(m, v));
}

template<typename T>
vector<vector<vector<T>>> vec3d(int n, int m, int k, T v){
    return vector<vector<vector<T>>>(n, vector<vector<T>>(m, vector<T>(k, v)));
}

template<typename T>
void print_vector(vector<T> v, char delimiter=' '){
    if(v.empty()) {
        cout << endl;
        return;
    }
    for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter;
    cout << v.back() << endl;
}

vector<int> zeta(vector<int> a, int n){
    vector<int> dp(1<<n);
    for(int i = 0; i < (1<<n); i++){
        dp[i] = a[i];
    }

    for(int j = 0; j < n; j++){
        for(int i = 0; i < (1 << n); i++){
            if(i & (1 << j)){
                dp[i] += dp[i ^ (1 << j)];
            }
        }
    }
    return dp;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int n, m; cin >> n >> m;
    vector<int> a(n);
    for(int i = 0; i < n; i++) cin >> a[i];
    vector<int> v(1<<m);
    for(int i = 0; i < n; i++){
        string s; cin >> s;
        int x = 0;
        for(int j = 0; j < m; j++){
            if(s[j] == 'o') x += 1<<j;
        }
        v[x] += a[i];
    }
    auto u = zeta(v, m);
    vector<ll> dp(1<<m, 0ll);
    int all_bits = (1<<m)-1;
    for(int s = 0; s < (1<<m); s++){
        int t = all_bits-s;
        for(int i = 0; i < m; i++){
            if(s&(1<<i)) continue;
            ll sum = u[t]-u[t-(1<<i)];
            chmax(dp[s+(1<<i)], dp[s]+sum*sum);
        }
    }
    cout << dp[all_bits] << endl;

}