#include<stdio.h>
int N,M,viz[1001];
int a[1000][1000];
void citire()
{
  int i,x,y;
  FILE *in = fopen("dfs.in","rt");
  fscanf(in,"%d %d",&N,&M);
  for(i=1;i<=M;i++)
  {
    fscanf(in,"%d %d",&x,&y);
    a[x][y]=a[y][x]=1;
  }
  fclose(in);
}
void df(int k)
{
  int i;
  viz[k]=1;
  for(i=1;i<=N;i++)
  if(a[k][i]&&!viz[k]) 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;
}