#include<stdio.h>

#include<math.h>

#include<string.h>

#include<algorithm>

#include<iostream>

#include<queue>

#include<map>

#include<vector>

int pre[];

int find(int x)

{

  int r=x;

  while(pre[r]!=r)

    r=pre[r];

  int i=x,j;

  while(i!=r)

  {

    j=pre[i];

    pre[i]=r;

    i=j;

  }

  return r;

}

int main()

{

  int n,m,i,x,y,sum;

  while(scanf("%d %d",&n,&m)!=EOF&&n)

  {

    for(i=;i<=n;i++)

      pre[i]=i;

     sum=n-;

    for(i=;i<=m;i++)

    {

      scanf("%d %d",&x,&y);

      x=find(x);

      y=find(y);

      if(x!=y)

      {

        sum--;

        pre[y]=x;

      }

    }

    printf("%d\n",sum);

  }

  return ;

}