import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const N = readInt;
      const M = readInt;
      auto V = new long[N];
      foreach (i; 0 .. N) {
        V[i] = readLong;
      }
      auto S = new string[N];
      foreach (i; 0 .. N) {
        S[i] = readToken;
      }
      
      auto fs = new long[1 << M];
      foreach (i; 0 .. N) {
        int p;
        foreach (j; 0 .. M) if (S[i][j] == 'o') {
          p |= 1 << j;
        }
        fs[p] += V[i];
      }
      
      // xx????
      foreach (j; 0 .. M) {
        foreach (p; 0 .. 1 << M) if (!(p & 1 << j)) {
          fs[p | 1 << j] += fs[p];
        }
      }
      
      const all = (1 << M) - 1;
      auto dp = new long[1 << M];
      foreach (p; 0 .. 1 << M) {
        foreach (j; 0 .. M) if (!(p & 1 << j)) {
          // xxo??? = xx???? - xxx???
          const pp = p | 1 << j;
          const score = fs[all - p] - fs[all - pp];
          chmax(dp[pp], dp[p] + score^^2);
        }
      }
      writeln(dp[$ - 1]);
    }
  } catch (EOFException e) {
  }
}