#include <cstdio>#include <iostream>#include <algorithm>#include <cstdlib>#include <cstring>#include <queue>#define N 100100#define M 2000100using namespace std;struct sss{    int num;    int du;};int n, m;int p[N] = {0}, next[M], v[M], bnum = 0;int du[N] = {0}, vis[N] = {0}, qu[N];priority_queue<sss> q;int hcolor[N] = {0}, color[N] = {0}, colornum = 0, huse[N] = {0};bool operator < (sss x, sss y){    return x.du < y.du;}void addbian(int x, int y){    bnum++; next[bnum] = p[x]; p[x] = bnum; v[bnum] = y;    bnum++; next[bnum] = p[y]; p[y] = bnum; v[bnum] = x;}void make_queue(){    for (int i = 1; i <= n; ++i)    {        sss x; x.num = i; x.du = 0;        q.push(x);    }    int dc = 0;    while (dc < n)    {        sss y = q.top(); q.pop();        while (vis[y.num])        {            y = q.top();            q.pop();        }        vis[y.num] = 1;        qu[++dc] = y.num;        int k = p[y.num]; sss ne;        while (k)        {            if (!vis[v[k]])            {                du[v[k]]++; ne.du = du[v[k]];                ne.num = v[k]; q.push(ne);            }            k = next[k];        }    }}void color_dian(){    for (int i = 1; i <= n; ++i)    {        int x = qu[i];        int k = p[x];        int all = 0;        while (k)        {            if (color[v[k]] != 0) all = 1;            huse[color[v[k]]] = x;            k = next[k];        }        int pd = 0;        for (int i = 1; i <= colornum; ++i)            if (huse[i] != x)            {                pd = 1;                color[x] = i;                break;            }        if (!pd) color[x] = ++colornum;    }    printf("%d\n", colornum);}int main(){    scanf("%d%d", &n, &m);    for (int i = 1; i <= m; ++i)    {        int x, y; scanf("%d%d", &x, &y);        addbian(x, y);    }    make_queue();    color_dian();    return 0;}