// ===== template.hpp =====
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#define OVERRIDE(a, b, c, d, ...) d
#define REP2(i, n) for (i32 i = 0; i < (i32) (n); ++i)
#define REP3(i, m, n) for (i32 i = (i32) (m); i < (i32) (n); ++i)
#define REP(...) OVERRIDE(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define PER(i, n) for (i32 i = (i32) (n) - 1; i >= 0; --i)
#define ALL(x) begin(x), end(x)

using namespace std;

using u32 = unsigned int;
using u64 = unsigned long long;
using u128 = __uint128_t;
using i32 = signed int;
using i64 = signed long long;
using i128 = __int128_t;

template <typename T>
using Vec = vector<T>;

template <typename T>
bool chmin(T &x, const T &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T>
bool chmax(T &x, const T &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}

[[maybe_unused]] constexpr i32 INF = 1000000100;
[[maybe_unused]] constexpr i64 INF64 = 3000000000000000100;

struct FastIO {
    FastIO() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
        cout << fixed << setprecision(10);
    }
} fast_io;
// ===== template.hpp =====

#ifdef DEBUGF
#include  "../new_library/other/debug.hpp"
#else
#define DBG(x) (void) 0
#endif

int main() {
    i32 n, m;
    cin >> n >> m;
    Vec<i64> v(n);
    REP(i, n) {
        cin >> v[i];
    }
    Vec<string> s(n);
    REP(i, n) {
        cin >> s[i];
    }
    
    Vec<i64> tmp(1 << m);
    REP(i, n) {
        i32 st = 0;
        REP(j, m) {
            if (s[i][j] == 'o') {
                st ^= 1 << j;
            }
        }
        DBG(st);
        tmp[st] += v[i];
    }
    REP(i, m) {
        REP(j, 1 << m) {
            if ((j >> i) & 1) {
                tmp[j] += tmp[j ^ (1 << i)];
            }
        }
    }
    
    Vec<i64> sum(1 << m);
    i64 v_sum = accumulate(ALL(v), 0LL);
    REP(i, 1 << m) {
        sum[i] = v_sum - tmp[((1 << m) - 1) ^ i];
    }
    DBG(sum);
    
    Vec<i64> dp(1 << m, -INF64);
    REP(i, m) {
        dp[1 << i] = sum[1 << i] * sum[1 << i];
    }
    REP(i, 1, 1 << m) {
        REP(j, m) {
            if ((i >> j) & 1) {
                continue;
            }
            i64 diff = sum[i ^ (1 << j)] - sum[i];
            chmax(dp[i ^ (1 << j)], dp[i] + diff * diff);
        }
    }
    DBG(dp);
    cout << dp[(1 << m) - 1] << '\n';
}