#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#define IN 100000
#define FOR(a) for(int i=1;i<=a;i++)
using namespace std;
int num[IN],f[IN][2],m,n;
bool vis[IN];
inline void addedge(int a,int b)
{
	f[a][++num[a]]=b;
	f[b][++num[b]]=a;
	vis[a]=1;vis[b]=1;
}
inline void deal(int a)
{
		vis[a]=0;//cout<<i<<endl;
		num[f[a][1]]--;if(num[f[a][1]]<=2&&vis[f[a][1]])deal(f[a][1]);
		if(num[f[a][1]]==0)vis[f[a][1]]=0;
		if(f[a][2]!=0)num[f[a][2]]--;if(num[f[a][2]]<=2&&vis[f[a][2]])deal(f[a][2]);
		if(num[f[a][2]]==0)vis[f[a][2]]=0;
}
int main()
{
    freopen("asm_game.in","r",stdin); 
    freopen("asm_game.out","w",stdout);
	int ans=0;
	cin>>n>>m;
	FOR(n)vis[i]=1;
	FOR(m)
	{  int a,b;
		cin>>a>>b;
		addedge(a,b);
	}
	FOR(n)if(num[i]<=2)deal(i);
	FOR(n)if(vis[i]){ans=i;vis[i]=0;break;}
	if(ans==0){cout<<0;return 0;}
//	FOR(n)if(vis[i])cout<<i<<endl;
	FOR(n) if(vis[i])ans=ans xor i;
	cout<<ans;
	
 }