how many tables

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int father[1100];
int find(int x)
{
 return x==father[x]?x:father[x]=find(father[x]);
}
void merge(int x,int y)
{
  x=find(x),y=find(y);
  if(x!=y)
  father[x]=y;
}
int main( )
{
 int P,N,M,d[1100],count,i,j,a,b;
 scanf("%d",&P);
 while(P--)
 {
  scanf("%d%d",&N,&M);
  count=0;
  memset(d,0,sizeof(d));
  for(i=1;i<=1100;i++)
  father[i]=i;
  for(i=1;i<=M;i++)
  {
   scanf("%d%d",&a,&b);
   if(find(a)!=find(b))
     merge(a,b);
  }
  for(i=1;i<=N;i++)
  d[find(i)]++; 
  for(i=1;i<=N;i++)
  if(d[i]!=0)
  count++;
  printf("%d\n",count);
}
  return 0;
}