#include<bits/stdc++.h>
using namespace std;

#define int long long 
#define F first 
#define S second 
#define pb push_back 

const int mol=998244353;

char a[5][105];
int dp[105][105][105];


int okbc[105][105][105],okac[105][105][105],okab[105][105][105];
void solve(){
    int n,q;
    cin>>n>>q;

    int cc=0;
    for(int i=1;i<=3;i++) for(int j=1;j<=n;j++) cin>>a[i][j];

    for(int i=1;i<=3;i++) for(int j=1;j<=n;j++){
        if(a[i][j]!='#') cc++;
    }
    if(cc<q){
        cout<<"-1\n";
        return;
    }

    int l=0,r=50000;
    while(l<r){
        int mid=l+r+1>>1;

        for(int i=0;i<=n;i++) for(int j=0;j<=n;j++) for(int k=0;k<=n;k++) dp[i][j][k]=0,okab[i][j][k]=0,okac[i][j][k]=0,okbc[i][j][k]=0;
        for(int i=n;i>=0;i--){
            for(int j=n;j>=0;j--){
                for(int k=n;k>=0;k--){
                    bool ok=1;
                    if(a[1][i]=='#') ok=0;
                    if(a[2][j]=='#') ok=0;
                    if(a[3][k]=='#') ok=0;
                    if((j-i)*(j-i)+1<mid&&i&&j) ok=0;
                    if((k-i)*(k-i)+4<mid&&i&&k) ok=0;
                    if(j&&(k-j)*(k-j)+1<mid&&k) ok=0;
                    if(!ok){
                        okab[i][j][k]=okab[i][j][k+1];
                        okac[i][j][k]=okac[i][j+1][k];
                        okbc[i][j][k]=okbc[i+1][j][k];
                    }
                    else
                    okab[i][j][k]=k,okac[i][j][k]=j,okbc[i][j][k]=i;
                }
            }
        }
        
        int ans=0;
        int t=sqrt(mid);
        while(t*t>=mid) t--;
        while(t*t<mid) t++;
        for(int i=0;i<=n;i++){
            for(int j=0;j<=n;j++){
                for(int k=0;k<=n;k++){
                    bool ok=1;
                    if(a[1][i]=='#') ok=0;
                    if((j-i)*(j-i)+1<mid&&i&&j) ok=0;
                    if(a[2][j]=='#') ok=0;
                    if(k){
                        if((k-i)*(k-i)+4<mid&&i) ok=0;
                        if(j&&(k-j)*(k-j)+1<mid) ok=0;
                    }
                    if(a[3][k]=='#') ok=0;
                    if(i) dp[i][j][k]=max(dp[i][j][k],dp[i-1][j][k]);
                    if(j) dp[i][j][k]=max(dp[i][j][k],dp[i][j-1][k]);
                    if(k) dp[i][j][k]=max(dp[i][j][k],dp[i][j][k-1]);
                    if(!ok){
                        continue;
                    }
                    int u=0;if(i) u++;if(j) u++;if(k) u++;
                    dp[i][j][k]=max({u,dp[i][j][k]});
                    

                    if(i+t<=n&&okbc[i+t][j][k]&&okbc[i+t][j][k]>=max({i,j,k})) dp[okbc[i+t][j][k]][j][k]=max(dp[okbc[i+t][j][k]][j][k],dp[i][j][k]+1);
                    if(j+t<=n&&okac[i][j+t][k]&&okac[i][j+t][k]>=max({i,j,k})) dp[i][okac[i][j+t][k]][k]=max(dp[i][okac[i][j+t][k]][k],dp[i][j][k]+1);
                    if(k+t<=n&&okab[i][j][k+t]&&okab[i][j][k+t]>=max({i,j,k})) dp[i][j][okab[i][j][k+t]]=max(dp[i][j][okab[i][j][k+t]],dp[i][j][k]+1);
                    ans=max(ans,dp[i][j][k]);
                }
            }
        }
        if(ans>=q) l=mid;
        else r=mid-1;
    }
    // cout<<l<<"\n";
    cout<<fixed<<setprecision(6)<<sqrt(l)<<"\n";
}

signed main(){
    ios::sync_with_stdio(0);cin.tie(0);
    // double t1=(double)clock()/CLOCKS_PER_SEC;
    solve();
    // double t2=(double)clock()/CLOCKS_PER_SEC;
    // cout<<fixed<<setprecision(10)<<t2-t1<<"\n";
    return 0;
}