#include <cstdlib>
#include <cstdio>
#include <vector>
#include <queue>
#include <string>
#include <cstring>
#include <algorithm>
using namespace std;
const int MAXN=2010;
int flag[MAXN],a,b,N,M;
vector<int> map[MAXN],ans;

inline void init()
{
	scanf("%d%d\n",&N,&M);
	for(int i=1;i<=M;i++)
	{
		scanf("%d%d\n",&a,&b);
		map[a].push_back(b);
		map[b].push_back(a);
	}
}

queue<int> q;
inline void check(int k)
{
	memset(flag,0,sizeof(flag));
	while(q.size()) q.pop();
	q.push(1); flag[1]=1;int u,v;
	while(q.size())
	{
		u=q.front(); q.pop();
		for(unsigned int i=0;i<map[u].size();i++)
		{
			v=map[u][i];
			if(v==k) continue;
			if(flag[v]) continue;
			if(v==N) return;
			flag[v]=1;q.push(v);
		}
	}
	ans.push_back(k);
}

int main()
{
	freopen("running.in","r",stdin);
	freopen("running.out","w",stdout);
	init();
	for(int i=2;i<=N-1;i++)
		check(i);
	printf("%d\n",ans.size());
	for(unsigned int i=0;i<ans.size();i++)
		printf("%d ",ans[i]);
	return 0;
}