#include <iostream>
#include <stdio.h>
#include <vector>
#define NMax 100002
using namespace std;
vector<int> Graf[NMax];
int N,M,solution,x,y;
bool uz[NMax];

void Read()
{
    freopen("dfs.in","r",stdin);
    scanf("%d%d",&N,&M);
    for(int i=1;i<=M;i++)
    {
        scanf("%d%d",&x,&y);
        Graf[x].push_back(y);
        Graf[y].push_back(x);
    }
}

void DFS(int nod)
{
    for(vector<int>::iterator it=Graf[nod].begin();Graf[nod].end()!=it;it++)
    {
        if(uz[*it]==false)
        {
            uz[*it]=true;
        }
    }
}

void Write()
{
    freopen("dfs.out","w",stdout);
    for(int i=1;i<=N;i++)
    {
        if(uz[i]==false)
        {
            DFS(i);
            solution++;
        }
    }
    printf("%d",solution);
}

int main()
{
   Read();
   Write();
}