#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <vector>
#include <queue>
#include <iomanip>
using namespace std;
const int N = 105;
const double eps = 1e-8;
int n, k;
char c[5][N];
bool p[5][N];

bool is_ok(int x, int y, double num) {
	for (int i = 1; i <= 3; i++) {
		for (int j = 1; j <= n; j++) {
			if (!p[i][j] || c[i][j] == '#') continue;
			if ( (x - i) * (x - i) + (y - j) * (y - j) < num*num ) return 0;
		}
	}
	return 1;
}

bool check(int s, double num, int d) {
	for (int i = s; i <= n; i += d) {
		p[1][i] = 1;
	}
	for (int i = 2; i <= 3; i++) {
		for (int j = 1; j <= n; j++) {
			if (is_ok(i, j, num)) {
				p[i][j] = 1;
			}
		}
	}
	int cnt = 0;
	for (int i = 1; i <= 3; i++) {
		for (int j = 1; j <= n; j++) {
			if (p[i][j] && c[i][j] == '.') {
				++cnt;
			}
		}
	}
	return (cnt >= k);
}

bool Check(double num) {
	int d = int(ceil(num));
	for (int i = 1; i <= n; i++) {
		memset(p, 0, sizeof(p));
		if (check(i, num, d)) return 1;
	}
	return 0;
}

int main() {
	cin >> n >> k;
	int tot = 0;
	for (int i = 1; i <= 3; i++) {
		for (int j = 1; j <= n; j++) {
			cin >> c[i][j];
			if (c[i][j] == '.') ++tot;
		}
	}
	if (tot < k) {
		cout << -1 << endl;
		return 0;
	}
	double l = 1.0, r = sqrt((n-1) * (n-1) + 4.0);
	double ans = 1.0;
	while (r - l > eps) {
		double mid = (l + r) / 2.0;
		if (Check(mid)) {
			ans = mid;
			l = mid;
		}
		else {
			r = mid;
		}
	}
	cout << fixed << setprecision(10) << ans << endl;
	return 0;
}