#include <iostream>
#include <fstream>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <vector>

using namespace std;

ifstream f("dfs.in");
ofstream d("dfs.out");
int search_unmarked(vector<int> b,int n);
void mark(int **a,vector<int> &b,int n,int x,int y);

int main()
{
    int n,m,i,x,y;
    f>>n;
    f>>m;

    vector<int> b(n,0);
    int **a;
    a = new int*[n];
    for(i=0;i<n;i++)
        a[i] = new int[n];
    for(i=0;i<n;i++)
        for(int j=0;j<n;j++)
            a[i][j]=0;

    for(i=1;i<=m;i++)
    {
        f>>x;
        f>>y;
        a[x][y]=1;
        a[y][x]=1;
    }
    srand (time(NULL));
    x=rand() % n;
    i=1;
    mark(a,b,n,x,i);
    while(search_unmarked(b,n) != -1)
    {
        x=search_unmarked(b,n);
        i++;
        mark(a,b,n,x,i);
    }
    int comp_conex=0;

    for(i=0;i<n;i++)
        if(b[i]>comp_conex)
            comp_conex=b[i];
    d<<comp_conex;
    return 0;
}

int search_unmarked(vector<int> b,int n)
{
    for(int i=0;i<=n;i++)
        if(b[i]==0)
            return i;
    return -1;
}

/*void mark(int **a,vector<int> b,int n,int x,int y)
{
    b[x]=y;
    for(int i=0;i<n;i++)
        if(a[x][i]==1 && b[i]!=y)
        {
            b[i]=y;
            mark(a,b,n,i,y);
        }
}*/

void mark(int **a, vector<int> &b, int n,int i, int y)
{
    int j;
    printf("\n%d",i);
    b[i]=y;
    for(j=0;j<n;j++)
        if(!b[j] && a[i][j]==1)
            mark(a,b,n,j,y);
}