#include <fstream>
#include <vector>
#define NMAX 100002
using namespace std;
ifstream fin("dfs.in");
ofstream fout("dfs.out");

vector <int> graf[NMAX];
int fr[NMAX];
int contor=0;

int dfs(int k)
{
    for(vector <int> :: iterator i=graf[k].begin();i!=graf[k].end();i++)
    {
        if(fr[*i]==0)
        {
            fr[*i]=1;
            dfs(*i);
            contor++;
        }
    }
}

int main()
{
    int n,m,x,y;
    fin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        fin>>x>>y;
        graf[x].push_back(y);
        graf[y].push_back(x);
    }
    for(int i=1;i<=n;i++)
    {
        if(fr[i]==0)
        {
            fr[i]=1;
            dfs(i);
        }
    }
    fout<<contor;
    return 0;
}