#include <iostream>
#include <cstdio>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#include <string>
#include <cstring>
#include <cctype>
#include <utility>
#include <cmath>

using namespace std;
int cnt=0;
int n, K;
string s[200];
char t[100][20000];
char vs[20000];
int vlen=0;
int len[201];
int tl[201];

void get (int i, int k, int sr, int res) {
    if (k > K)  {
            cnt = max(cnt, res);
            return;
    }
    char ok = 'W';
        for (int f = len[i], g = vlen; f > 0 && g > 0; f--, g--)
            if (vs[g] != t[i][f]) {
                if (vs[g] == 'W')
                    ok = 'B';
                else
                    ok = 'W';
                break;
                }
        vlen++;
        vs[vlen] = ok;
        len[i]++;
        t[i][len[i]] = (ok == 'W' ? 'B' : 'W');
        int vl = vlen;
        for (int f = 0; f < n; f++)
            tl[f] = len[f];
        get ((i + 1) % n, k + 1, 1, res + (ok == 'W'));
        vlen = vl;
        for (int f = 0; f < n; f++)
            len[f] = tl[f];
        if (sr < 2)
            get (i, k + 1, 2, res + (ok == 'W'));
}

int main () {
    freopen ("checkers.in", "r", stdin);
    freopen ("checkers.out", "w", stdout);

    cin >> n >> K;
    for (int i = 0; i < n; i++) {
        cin >> s[i];
        len[i] = s[i].size();
        for (int j = 0; j < len[i]; j++)
            t[i][j + 1] = s[i][j];
    }
    get (0, 1, 1, 0);
    cout << cnt;
    return 0;
}