1 #include "stdio.h"
2 int bin[1002];
3
4 int findx(int x)
5 {
6 int r,j,i;
7 r = x;
8 while (bin[r] != r)
9 r = bin[r];
10 i = x;
11 while (i != r)
12 {
13 j = bin[i];
14 bin[i] = r;
15 i = j;
16 }
17 return r;
18 }
19
20 void merge(int x,int y)
21 {
22 int fx,fy;
23 fx = findx(x);
24 fy = findx(y);
25 if(fx != fy)
26 bin[fx] = fy;
27 }
28
29 int main()
30 {
31 int n,m,i,x,y,count;
32 while(scanf("%d",&n),n)
33 {
34 for(i=1; i<=n; i++)
35 bin[i] = i;
36 for(scanf("%d",&m); m>0; m--)
37 {
38 scanf("%d %d",&x,&y);
39 merge(x,y);
40 }
41 for(count=-1, i=1; i<=n; i++)
42 if(bin[i] == i)
43 count ++;
44 printf("%d\n",count);
45 }
46 }
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