#include <bits/stdc++.h>
#define rep1(i, l, r) for (int i = l; i <= int(r); ++i)
#define rep2(i, l, r) for (int i = l; i >= int(r); --i)
#define rer(i, l, r, a) rep1(i, l, r) read(a[i])
#define ptc putchar
#define il inline
#define eb emplace_back
#define ef emplace_front
#define mp make_pair
#define fst first
#define snd second
#define sqr(x) ((x) * (x))
#define ls(x) x << 1
#define rs(x) x << 1 | 1
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
// typedef __int128 bll;
// typedef unsigned __int128 ubll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 2e6 + 10, LOGN = log2(MAXN) + 1, inf = ~0U >> 2, INF = ~0U >> 1;
const int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0};
namespace stupid_lrc {
	template <typename T> il bool read(T &x) {
		x = 0; bool f = false; char ch;
 		while (!isdigit(ch = getchar())) {
			f ^= !(ch ^ '-');
			if (ch == EOF) return false;
		}
		while (isdigit(ch)) x = (x << 1) + (x << 3) + (ch & 15), ch = getchar();
		if (f) x = ~x + 1; return true;
	}
	il int read() {int x; read(x); return x;}

	template <typename T> il bool read(pair <T, T> &x) {return read(x.fst) && read(x.snd);}

	template <typename T> il void gmin(T &x, T y) {x = x < y ? x : y;}

 	template <typename T> il void gmax(T &x, T y) {x = x > y ? x : y;}

	template <typename T, typename ...L>
	il bool read(T &x, L &...y) {return read(x) && read(y...);}

	template <typename T> il T lowbit(const T &x) {return x & -x;}
}
using namespace stupid_lrc;
int n, k, dis[MAXN], vis[MAXN];

int main() {
	read(n, k); queue <int> q;
	rep1(i, 0, (1 << k) - 1) dis[i] = inf;
	rep1(i, 1, n) {
		int x = 0; char ch;
 		while (!isdigit(ch = getchar()));
		while (isdigit(ch)) x = (x << 1) + (ch & 15), ch = getchar();
		dis[x] = 0; q.emplace(x);
	}
	while (q.size()) {
		int x = q.front(); q.pop();
		if (vis[x]) continue;
		vis[x] = 1;
		rep1(i, 0, k - 1) {
			int v = x ^ (1 << i);
			if (dis[v] > dis[x] + 1) dis[v] = dis[x] + 1, q.emplace(v);
		}
	} int mx = -1, ans = -1;
	rep1(i, 0, (1 << k) - 1) if (dis[i] > mx) mx = dis[ans = i];
	rep2(i, k - 1, 0) printf("%d", ans >> i & 1);
	return 0;
}