#include<cstdio>
#include<queue>
#include<vector>
#include<algorithm>
#include<cstring>
#include<iostream>
using namespace std;
vector<int>p[500010];
int m,n;
bool vis[100100];
int main()
{
	freopen("asm_game.in","r",stdin);
	freopen("asm_game.out","w",stdout);
	cin>>n>>m;
	for (int i=1;i<=n;i++)
	 vis[i]=true;
	for (int i=1;i<=m;i++)
	{
		int u,v;
		cin>>u>>v;
		p[u].push_back(v);
		p[v].push_back(u);
	}
	for (int k=1;k<=n;k++)
	{
		int v=1;
		for (int i=1;i<=n;i++)
		{
			int sum=0;
			for (int j=0;j<p[i].size();j++)
			{
				if (vis[p[i][j]])
			 	sum++;
			}
			if (sum<3)
			{
		 		vis[i]=false;
                v=0;	 	    
			}
		}
		if (v) break;
	}
	int p=1;
	int ans=0;
	for (int i=1;i<=n;i++)
	{
		if (vis[i])
		{
		    ans=ans^i;
            p=0;    	
		}
 	}
 	//for (int i=1;i<=n;i++)
 	 //if (vis[i])
 	 //cout<<i<<endl;
 	if (p) cout<<0;
 	else cout<<ans;
 	return 0;
}