#include <bits/stdc++.h>

using namespace std;

ifstream in("dfs.in");
ofstream out("dfs.out");

int n, m, a[100001][100001], v[100001];

void dfs(int k, int val)
{
    v[k] = val;
    for(int i = 1 ; i <= n; i++)
    {
        if(a[i][k] == 1 && v[i] == 0)
        {
            dfs(i, val);
        }
    }
}

int main()
{
    in >> n >> m;
    for(int i = 1; i <= m; i++)
    {
        int x, y;
        in >> x >> y;
        a[x][y] = a[y][x] = 1;
    }
    int val = 1;
    dfs(1, val);
    bool c = true;
    while(c)
    {
        c = false;
        for(int i = 1 ; i <= n; i++)
        {
            if(v[i] == 0)
            {
                dfs(i, ++val);
                c = true;
            }
        }
    }
    int maxim = 0;
    for(int i = 1; i <= n; i++)
    {
        maxim = max(maxim, v[i]);
    }
    out << maxim;
    return 0;
}