#include<stdio.h>
int a[1000][1000];
int viz[1000],N,M;
void citire()
{
  int i;
  FILE * in=fopen("dfs.in","rt");
  fscanf(in,"%d %d", &N,&M);
  for(i=1;i<=m;i++)
  {
    int x,y;
    fscanf(in,"%d %d",&x,&y);
    a[x][y]=a[y][x]=1;
  }
  fclose(in);
}
void df(int st)
{
   int i;
   viz[st]=1;
   for(i=1;i<=n;i++)
   if(viz[i]==0&&a[st][viz]==1)df(i);
}
int main()
{
  int i,nr=0;
  citire();
  for(i=1;i<=n;i++)
  if(!viz[i]){df(i);nr++}
  FILE *out=fopen("dfs.out","wt")
  fprintf(out,"%d",nr);
  return 0;
}