#include <bits/stdc++.h>
#define ff first
#define ss second
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int SZ = 110;

int n, s, a[3][SZ];

int dp[SZ][SZ][1 << 6], blk[SZ];
int ds(pii p, pii q) {
	return (p.ff - q.ff) * (p.ff - q.ff) + (p.ss - q.ss) * (p.ss - q.ss);
}

int cost[SZ][SZ][1 << 6][1 << 6];

int main() {
	cin.tie(0); ios_base::sync_with_stdio(0);

	cin >> n >> s;
	for (int t = 0; t < 3; t++) {
		string S;
		cin >> S;

		for (int i = 1; i <= n; i++) {
			if (S[i - 1] == '#') a[t][i] = true;
		}
	}

	a[0][0] = a[1][0] = a[2][0] = true;
	for (int i = 1; i <= n; i++) {
		for (int t = 0; t < 3; t++) blk[i] ^= (1 - a[t][i]) << t;
		for (int t = 0; t < 3; t++) blk[i] ^= (1 - a[t][i - 1]) << (t + 3);
	}
	
	dp[0][0][0] = 1e9;
	for (int k = 1; k <= s; k++) {
		for (int i = 1; i <= n; i++) {
			for (int msk = 0; msk < (1 << 6); msk++) {
				if ((blk[i] & msk) != msk) continue;

				// case 1. from i - 1
				if (k >= __builtin_popcount(msk & 7) && __builtin_popcount(msk & 7) != 0) {
					for (int up = 0; up < (1 << 3); up++) {
						int prv = (msk >> 3) | (up << 3);
						if ((blk[i - 1] & prv) != prv) continue;

						if (cost[i][i - 1][msk][prv] == 0) {
							vector<pii> L, R;
							for (int t = 0; t < 3; t++) if (msk >> t & 1) R.push_back({t, i});
							for (int t = 0; t < 3; t++) if (prv >> t & 1) L.push_back({t, i - 1});
							for (int t = 0; t < 3; t++) if (prv >> (t + 3) & 1) L.push_back({t, i - 2});

							int minv = 1e9;
							for (int i = 0; i < R.size(); i++) for (int j = 0; j < i; j++) {
								minv = min(minv, ds(R[i], R[j]));
							}
							for (pii p : L) for (pii q : R) {
								minv = min(minv, ds(p, q));
							}
							cost[i][i - 1][msk][prv] = minv;
						}
						dp[k][i][msk] = max(dp[k][i][msk], min(dp[k - __builtin_popcount(msk & 7)][i - 1][prv], cost[i][i - 1][msk][prv]));
					}
				}
				// case 2. from before i - 1
				if (k >= __builtin_popcount(msk) && __builtin_popcount(msk) != 0) {
					for (int j = 0; j < i - 1; j++) {
						for (int prv = 0; prv < (1 << 6); prv++) {
							if ((blk[j] & prv) != prv) continue;

							if (cost[i][j][msk][prv] == 0) {
								vector<pii> L, R;
								for (int t = 0; t < 3; t++) if (msk >> t & 1) R.push_back({t, i});
								for (int t = 0; t < 3; t++) if (msk >> (t + 3) & 1) R.push_back({t, i - 1});
								for (int t = 0; t < 3; t++) if (prv >> t & 1) L.push_back({t, j});
								for (int t = 0; t < 3; t++) if (prv >> (t + 3) & 1) L.push_back({t, j - 1});

								int minv = 1e9;
								for (int i = 0; i < R.size(); i++) for (int j = 0; j < i; j++) {
									minv = min(minv, ds(R[i], R[j]));
								}
								for (pii p : L) for (pii q : R) {
									minv = min(minv, ds(p, q));
								}
								cost[i][j][msk][prv] = minv;
							}
							dp[k][i][msk] = max(dp[k][i][msk], min(dp[k - __builtin_popcount(msk)][j][prv], cost[i][j][msk][prv]));
						}
					}
				}
			}
		}
	}
	int ans = 0;
	for (int i = 0; i <= n; i++) {
		for (int msk = 0; msk < (1 << 6); msk++) {
			ans = max(ans, dp[s][i][msk]);
		}
	}
	if (ans == 0) return !(cout << "-1\n");

	cout.precision(10);
	cout << fixed << sqrt(ans) << '\n';
}