#include <bits/stdc++.h>

using namespace std;

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

int a[10001][10001];

int n, m;

int viz[100001];

void dfs(int k, int def)
{
    viz[k] = def;
    for(int i = 1; i <= n; i++)
    {
        if(a[k][i] == 1 && !viz[i])
        {
            dfs(i, def);
            viz[i] = def;
        }
    }
}


int main()
{
    in >> n >> m;
    int l, c;
    while(m--)
    {
        in >> l >> c;
        a[l][c] = 1;
        a[c][l] = 1;
    }
    int cnt = 0;
    for(int i = 1; i <= n; i++)
    {
        if(viz[i] == 0)
        {
            dfs(i, cnt + 1);
            cnt++;
        }
    }
    out << cnt;
    return 0;
}