#include <bits/stdc++.h>

// #define int long long
#define ll long long
#define ull unsigned long long
#define db double
#define ld long double
#define rep(i,l,r) for (int i = (int)(l); i <= (int)(r); ++ i )
#define rep1(i,l,r) for (int i = (int)(l); i >= (int)(r); -- i )
#define il inline
#define fst first
#define snd second
#define ptc putchar
#define Yes ptc('Y'),ptc('e'),ptc('s'),puts("")
#define No ptc('N'),ptc('o'),puts("")
#define YES ptc('Y'),ptc('E'),ptc('S'),puts("")
#define NO ptc('N'),ptc('O'),puts("")
#define vi vector<int>
#define pb emplace_back
#define sz(x) (int)(x.size())
#define all(x) x.begin(),x.end()
#define me(a,x) memset(a,x,sizeof a)
#define get(x) ((x - 1) / len + 1)
#define debug() puts("------------")

using namespace std;
typedef pair<int,int> PII;
typedef pair<int,PII> PIII;
typedef pair<ll,ll> PLL;
namespace szhqwq {
    template<class T> il void read(T &x) {
        x = 0; T f = 1; char ch = getchar();
        while (ch < '0' || ch > '9') { if (ch == '-') f = -1; ch = getchar(); }
        while (ch >= '0' && ch <= '9') { x = (x << 3) + (x << 1) + (ch ^ 48); ch = getchar(); }
        x *= f;
    }
    template<class T,class... Args> il void read(T &x,Args &...x_) { read(x); read(x_...); }
    template<class T> il void print(T x) {
        if (x < 0) ptc('-'), x = -x; 
        if (x > 9) print(x / 10); ptc(x % 10 + '0');
    }
    template<class T,class T_> il void write(T x,T_ ch) { print(x); ptc(ch); }
    template<class T,class T_> il void chmax(T &x,T_ y) { x = x < (T)y ? (T)y : x; }
    template<class T,class T_> il void chmin(T &x,T_ y) { x = x > (T)y ? (T)y : x; }
    template<class T,class T_,class T__> il T qmi(T a,T_ b,T__ p) {
        T res = 1; while (b) {
            if (b & 1) res = res * a % p;
            a = a * a % p; b >>= 1;
        } return res;
    }
    template<class T> il T gcd(T a,T b) { if (!b) return a; return gcd(b,a % b); }
    template<class T,class T_> il void exgcd(T a, T b, T_ &x, T_ &y) {
        if (b == 0) { x = 1; y = 0; return; }
        exgcd(b,a % b,y,x); y -= a / b * x; return ;
    }
    template<class T,class T_> il T getinv(T x,T_ p) { 
        T inv,y; exgcd(x,(T)p,inv,y);
        inv = (inv + p) % p; return inv;
    }
} using namespace szhqwq;
const int N = 2e6 + 10,inf = 1e9,mod = 998244353;
const ull base = 131,base_ = 233;
const ll inff = 1e18;
const db eps = 1e-6;
int n,k,a[N]; bool vis[N];
int h[N],e[N * 20],ne[N * 20],idx;
int dist[N];

il void add(int a,int b) {
    e[idx] = b;
    ne[idx] = h[a];
    h[a] = idx ++;
}

il void bfs() {
    queue<int> q; me(dist,0x3f);
    rep(i,1,n) q.push(a[i]),vis[a[i]] = 1,dist[a[i]] = 0;
    while (sz(q)) {
        int u = q.front(); q.pop();
        for (int i = h[u]; ~i; i = ne[i]) {
            int j = e[i];
            if (dist[j] > dist[u] + 1) {
                dist[j] = dist[u] + 1;
                if (!vis[j]) vis[j] = 1,q.push(j);
            }
        }
    }
    return ;
}

il void solve() {
    //------------code------------
    read(n,k); me(h,-1);
    rep(i,1,n) {
        string s; cin >> s;
        rep(j,0,k - 1) a[i] += (1 << j) * (s[j] - '0');
    }
    rep(s,0,(1 << k) - 1)
        rep(p,0,k - 1) add(s,s ^ (1 << p));
    bfs();
    int ret = 0,mx = 0;
    rep(s,0,(1 << k) - 1) if (dist[s] > mx) mx = dist[s],ret = s;
    rep(p,0,k - 1) cout << (ret >> p & 1); puts("");
    return ;
}

il void init() {
    return ;
}

signed main() {
    // init();
    int _ = 1;
    // read(_);
    while (_ -- ) solve();
    return 0;
}