#include <bits/stdc++.h>

using namespace std;

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

///sa zicem ca am matrice de adiacenta prima data
//int a[10005][10005];
//void read()
//{   int x, y;
//    fin >> n >> m;
//    for(int i = 1; i <= m; i ++)
//    {
//        fin >> x >> y;
//        a[x][y] = a[y][x] = 1;
//    }
//}

int n, m, nr_comp;
bool vis[100005];

vector < int > L[100005];

void read()
{
    int x, y;
    fin >> n >> m;
    for(int i = 1; i <= m; i ++)
    {
        fin >> x >> y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
}

void dfs(int k)
{
    vis[k] = 1;
    for(int i = 0; i < L[k].size(); i ++)
    {
        if(vis[L[k][i]] == 0)
        {
            vis[L[k][i]] = 1;
            dfs(i);
        }
    }
}

int main()
{
    read();
    dfs(1);
    nr_comp = 1;
    for(int i = 2; i <= n; i ++)
    {
        if(vis[i] == 0)
        {
            nr_comp++;
            dfs(i);
        }
    }
    fout << nr_comp;
    return 0;
}