#include <bits/stdc++.h>
using namespace std;
#define fastio (ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL))
typedef long long ll;
typedef long double lld;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
const int MAXSIZE = 2000000;
const long long INF = 1e9 + 5;
const double EPSILON = 1e-14;
const ll DIV = 2000003;
const long double pi = 3.14159265358979323846264338327950288419716939937510L;

int n, k;

string s[3];
int dp[105][10];
double dis[105][105][10][10];
double l;
int cnt;

int solve(int i, int a)
{
    if (i == 0)
    {
        return 0;
    }

    int &ret = dp[i][a];
    if (ret != -1)
        return ret;

    ret = 0;

    if (dis[i][i][a][a] >= l)
    {

        ret = __builtin_popcount(a);
    }

    for (int j = 1; j < i; j++)
    {
        for (int b = 1; b < 8; b++)
        {
            // cout << dis[j][i][b][a] << " " << l << "\n";
            if (dis[j][i][b][a] >= l && dis[j][i][b][a] < INF - EPSILON)
            {

                ret = max(ret, solve(j, b) + __builtin_popcount(a));
                // cout << ret << "\n";
            }
        }
    }

    cnt = max(cnt, ret);
    return ret;
}

int ok(double t)
{
    cnt = 0;
    l = t;
    memset(dp, -1, sizeof dp);
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j < 8; j++)
            solve(i, j);
    }
    // cout << cnt << "\n";
    return cnt >= k;
}

int main()
{
    fastio;
    cin >> n >> k;
    int nt = 0;
    for (int i = 0; i < 3; i++)
    {
        cin >> s[i];
        for (char j : s[i])
        {
            if (j == '#')
                nt++;
        }
        s[i] = '1' + s[i];
    }
    if (3 * n - nt < k)
    {
        cout << -1;
        return 0;
    }

    fill_n(&dis[0][0][0][0], 105 * 105 * 10 * 10, INF);

    for (int i = 1; i <= n; i++)
    {
        for (int j = i; j <= n; j++)
        {
            for (int v = 1; v < 8; v++)
            {
                for (int u = 1; u < 8; u++)
                {
                    if (u == 3 || u == 6 || u == 7)
                        dis[i][j][v][u] = min(dis[i][j][v][u], (double)1);
                    if (u == 5)
                        dis[i][j][v][u] = min(dis[i][j][v][u], (double)2);

                    for (int a = 0; a < 3; a++)
                    {
                        if ((v & (1 << a)) == 0)
                            continue;
                        if (s[a][i] == '#')
                        {
                            dis[i][j][v][u] = 0;
                            continue;
                        }

                        for (int b = 0; b < 3; b++)
                        {
                            if ((u & (1 << b)) == 0)
                                continue;
                            if (s[b][j] == '#')
                            {
                                dis[i][j][v][u] = 0;
                                continue;
                            }
                            if (i != j)
                                dis[i][j][v][u] = min(dis[i][j][v][u], sqrt((double)(i - j) * (i - j) + (double)(a - b) * (a - b)));
                        }
                    }
                    // cout << dis[i][j][v][u] << "\n";
                }
            }
        }
    }
    double l = 1, r = INF;

    for (int i = 0; i < 60; i++)
    {
        double m = (l + r) / (2.0);
        if (ok(m))
            l = m;
        else
            r = m;
    }
    cout.precision(10);
    cout << fixed;
    cout << l << "\n";

    return 0;
}