1 #include <iostream>
 2 #include <cstdio>
 3 using namespace std;
 4 int father[1010],sum;
 5 void set(int n)
 6 {
 7     for (int i=1; i<=n; i++)
 8         father[i]=i;
 9 }
10 int find(int a)
11 {
12     if (father[a]==a)
13         return a;
14     return father[a]=find(father[a]);
15 }
16 void Union(int x,int y)
17 {
18     x=find(x);
19     y=find(y);
20     if (x!=y)
21     {
22         sum--;
23         father[x]=y;
24     }
25 }
26 int main ()
27 {
28     int n,m;
29     while (scanf("%d",&n),n)
30     {
31         scanf ("%d",&m);
32         set(n);
33         sum=n-1;
34         while (m--)
35         {
36             int a,b;
37             scanf("%d%d",&a,&b);
38             Union(a,b);
39         }
40         printf ("%d\n",sum);
41     }
42     return 0;
43 }