#include <bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace __gnu_pbds;
using namespace std;
#define pb push_back
#define rep(i,x,y) for(register int i=x;i<=y;i++)
#define rep1(i,x,y) for(register int i=x;i>=y;--i)
#define int long long
#define fire signed
#define il inline
template<class T> il void print(T x) {
	if(x<0) printf("-"),x=-x;
	if (x > 9) print(x / 10);
	putchar(x % 10 + '0');
}
template<class T> il void in(T &x) {
    x = 0; char ch = getchar();
    int f = 1;
    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;
}
int T=1;
int n,k;
struct node{
	int p,s;
};
queue<node>q;
const int N=1<<20;
int vis[N],ans[N];
void bfs() {
	while(q.size()) {
		node x=q.front();
		q.pop();
		vis[x.p]=1;
		rep(j,0,k-1) {
			node y=x;
			y.p^=(1<<j);
			if(vis[y.p]) continue;
//			if(y.p==1) cout<<x.s+1<<endl;
			ans[y.p]=x.s+1;
			vis[y.p]=1;
			q.push({y.p,x.s+1});
		}
	}
}
void solve() {
	in(n),in(k);
	memset(ans,0x3f,sizeof ans);
	rep(i,1,n) {
		int now=0;
		rep(j,0,k-1) {
			char c;
			cin>>c;
			if(c=='1') now|=(1<<j);
		}
		ans[now]=false;
		vis[now]=1;
		q.push({now,0});
	}
	bfs();
	int res=0,id=0;
	rep(i,0,(1<<k)-1) {
		if(res<ans[i]) {
			res=ans[i];
			id=i;
		}
	}
	rep(i,0,k-1) cout<<((id>>i)&1);
}
fire main() {
	while(T--) {
		solve();
	}
	return false;
}