#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define X first
#define Y second
#define SZ(a) ((int)a.size())
#define pb push_back
#define ALL(v) v.begin(), v.end()

const int N = 105;

int n, k;
int mp[N];

int dp[N][(1<<6)];
int can[(1<<6)][(1<<3)];
int cnt[(1<<3)];

void smax(int &a, int b) {
    a = max(a, b);    
}

bool chk(ll h) {
    memset(dp, -1, sizeof(dp)); 
    memset(can, 0, sizeof(can));
    ll d = 1;
    while (d * d + 4 < h) d++;
    for (int I = 0; I < (1<<6); I++)
        for (int J = 0; J < (1<<3); J++) {
            bool ok = true; 
            for (int i = 0; i < 6; i++)
                if ((I>>i) & 1)
                    for (int j = 0; j < 3; j++)
                        if ((J>>j) & 1) {
                            ll x, y;
                            if (i < 3) x = d, y = abs(i - j);
                            else x = d + 1, y = abs((i - 3) - j);
                            if (x * x + y * y < h)
                                ok = false;
                        }
            for (int i = 0; i < 3; i++)
                if ((J>>i) & 1)
                    for (int j = i + 1; j < 3; j++)
                        if ((J>>j) & 1) {
                            ll x = abs(j - i);
                            if (x * x < h)
                                ok = false;
                        }
            can[I][J] = ok;
        }
    dp[0][0] = 0;
    for (int i = 1; i <= n; i++)
        for (int I = 0; I < (1<<3); I++)
            if ((I & mp[i]) == I && can[0][I])
                smax(dp[i][I], cnt[I]);
    for (int i = 0; i < n; i++)
        for (int I = 0; I < (1<<6); I++)
            if (dp[i][I] >= 0) {
                smax(dp[i + 1][(I<<3) & ((1<<6) - 1)], dp[i][I]);
                if (i + d <= n)
                    for (int J = 0; J < (1<<3); J++)
                        if ((J & mp[i + d]) == J && can[I][J]) {
                            int targ = (d == 1 ? ((J | (I<<3)) & ((1<<6) - 1)) : J); 
                            smax(dp[i + d][targ], dp[i][I] + cnt[J]);
                        }
            }
    int ans = 0;
    for (int I = 0; I < (1<<6); I++)
        ans = max(ans, dp[n][I]);
    // cerr << h << " " << sqrt(h) << " " << d << " " << ans << endl;
    return ans >= k;
}

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

    for (int i = 0; i < (1<<3); i++)
        cnt[i] = __builtin_popcount(i);

    cin >> n >> k;
    for (int i = 0; i < 3; i++) {
        string s;
        cin >> s;
        for (int j = 0; j < n; j++)
            if (s[j] == '.')
                mp[j + 1] += (1<<i);
    }
    ll l = 0, r = 20000; 
    while (l != r - 1) {
        ll h = (l + r) / 2; 
        if (chk(h)) l = h;
        else r = h;
    }
    if (!chk(l)) cout << -1 << endl;
    else cout << fixed << setprecision(12) << sqrt(l) << endl;
}