#include<stdio.h>
int a[100000]={0},b[100000][2]={0};
int main()
{
	freopen("asm_game.in","r",stdin);
	freopen("asm_game.out","w",stdout);
	int i,j,k,n,m,u,v,yi=0,flag=1;
	scanf("%d%d",&n,&m);
	for(i=1;i<=m;i++)
	{
		scanf("%d%d",&u,&v);
		a[u]++;a[v]++;
		b[i][0]=u;
		b[i][1]=v;
	}
	aa:for(i=1;i<=n;i++)
	{
	if(a[i]<3&&a[i]!=0)
	{a[i]=0;
	for(j=1;j<=m;j++)
	{if(b[j][0]==i){a[b[j][1]]--;b[j][0]=0;b[j][1]=0;flag=0;}
	else if(b[j][1]==i){a[b[j][0]]--;b[j][1]=0;b[j][0]=0;flag=0;}
	}}}
    if(flag==0){flag=1;goto aa;}
	for(i=1;i<=n;i++)
	{if(a[i]!=0&&flag==1){yi=i;flag=0;continue;}
	if(a[i]!=0&&flag==0){yi=yi^i;}
	}
	printf("%d",yi);
}