#include<stdio.h>

 int father[];

 int Find(int x)

 {

     if(x!=father[x])//注意这里是if不是while！

         father[x]=Find(father[x]);

     return father[x];

 }

 void Combine(int a,int b)

 {

     int fa=Find(a);

     int fb=Find(b);

     if(fa!=fb)

     {

         father[fa]=fb;

     }

 }

 int main()

 {

 //    freopen("in.txt","r",stdin);

     int n,m;

     int i;

     int a,b;

     while(~scanf("%d",&n))

     {

         if(n==)

         break;

         scanf("%d",&m);

         int sum=;

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

             father[i]=i;

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

         {

             scanf("%d%d",&a,&b);

             Combine(a,b);

         }

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

         {

             if(father[i]==i)

                 sum++;

         }

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

     }

     return ;

 }