#include<bits/stdc++.h>
using namespace std;
struct Edge { int v,w; };
vector <Edge> G[1<<10];
int n,m,k,dis[1<<10];
bool inq[1<<10],q[1<<11],p[1<<11];
bool spfa() {
	memset(dis,0x3f,sizeof(dis));
	memset(inq,0,sizeof(inq));
	dis[0]=0,inq[0]=1;
	queue <int> Q; Q.push(0);
	while(Q.size()) {
		int u=Q.front(); Q.pop(),inq[u]=false;
		for(auto e:G[u]) if(dis[e.v]>dis[u]+e.w) {
			dis[e.v]=dis[u]+e.w;
			if(dis[0]<0) return false;
			if(!inq[e.v]) inq[e.v]=true,Q.push(e.v);
		}
	}
	return dis[0]>=0;
}
bool check(int i) {
	for(int s=0;s<n;++s) G[s].clear();
	for(int s=0;s<n;++s) {
		int t=(s<<1)&(n-1);
		for(int c:{0,1}) {
			int l,r,z=s<<1|c;
			if(z<=i) l=r=p[z]-c;
			else l=-c,r=1-c;
			G[s].push_back({t|c,r});
			G[t|c].push_back({s,-l});
		}
	}
	return spfa();
}
signed main() {
	scanf("%d",&k),n=1<<(2*k),m=2*n;
	for(int i=0;i<m;++i) scanf("%1d",&q[i]),p[i]=q[i];
	if(check(m-1)) {
		for(int i=0;i<m;++i) printf("%d",q[i]);
		puts(""); return ;
	}
	for(int i=m-1;~i;--i) if(q[i]==0) {
		for(int j=0;j<i;++j) p[j]=q[j];
		p[i]=1;
		for(int j=i+1;j<m;++j) p[j]=0;
		if(!check(i)) continue;
		for(int j=i+1;j<m;++j) if(!check(j)) p[j]=1;
		for(int j=0;j<m;++j) printf("%d",p[j]);
		puts(""); return 0;
	}
	puts("-1");
}

answer.code: In function ‘int main()’:
answer.code:38:39: warning: format ‘%d’ expects argument of type ‘int*’, but argument 2 has type ‘bool*’ [-Wformat=]
   38 |         for(int i=0;i<m;++i) scanf("%1d",&q[i]),p[i]=q[i];
      |                                     ~~^  ~~~~~
      |                                       |  |
      |                                       |  bool*
      |                                       int*
answer.code:41:27: error: return-statement with no value, in function returning ‘int’ [-fpermissive]
   41 |                 puts(""); return ;
      |                           ^~~~~~
answer.code:37:14: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   37 |         scanf("%d",&k),n=1<<(2*k),m=2*n;
      |         ~~~~~^~~~~~~~~
answer.code:38:35: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   38 |         for(int i=0;i<m;++i) scanf("%1d",&q[i]),p[i]=q[i];
      |                              ~~~~~^~~~~~~~~~~~~