#include <bits/stdc++.h>
#define pb push_back

using namespace std;
ifstream fin("dfs.in");
ofstream fout("dfs.out");
const int N=100009;
int n,m,ans,d[N];
vector <int> v[N];
void dfs(int nod)
{
    d[nod]=1;
    for(auto it:v[nod])
        if(!d[it])
            dfs(it);
}
int main()
{
    fin.sync_with_stdio(false);
    fin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        int x,y;
        fin>>x>>y;
        v[x].pb(y);
        v[y].pb(x);
    }
    for(int i=1;i<=n;i++)
        if(!d[i])
            ans++,dfs(i);
    fout<<ans;
    return 0;
}