#include <fstream>
#include <vector>
using namespace std;

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

bool a[100001];
int u[200000];
vector<int> v[100001];

void bfs(int x)
{
    int j=0,m=0,i;
    for(a[x]=1,u[0]=x;j<=m;++j)
        for(i=0;i<v[u[j]].size();++i)
            if(a[v[u[j]][i]]==0)
            {
                a[v[u[j]][i]]=1;
                u[++m]=v[u[j]][i];
            }
}

int main()
{
    int n,m,i,x,y;
    fin>>n>>m;
    for(;m;m--)
    {
        fin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for(i=1;i<=n;++i)
        if(a[i]==0)
        {
            bfs(i);
            m++;
        }
    fout<<m;
}