1 #include <stdio.h>
 2 int city[10010];
 3 
 4 int find (int a)
 5 {
 6     if(city[a]!=a)
 7     city[a]=find(city[a]);
 8     return city[a];
 9 }  
10 
11 int main()
12 {
13     int m,n,i,a,b;
14     while(~scanf("%d",&m),m)
15     {
16         scanf("%d",&n);
17         for(i=1; i<=m; i++)
18         city[i]=i;
19         for(i=1; i<=n; i++)
20         {
21             scanf("%d %d",&a,&b);
22             a=find(a);
23             b=find(b);
24             city[a]=b;
25         }
26         int add_street=-1;
27         for(i=1;i<=m;i++)
28         {
29             if(city[i] == i)
30             add_street++;
31         }
32         printf("%d\n",add_street);
33     }
34     return 0;
35 }