More is better

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define maxn 10000010 
int father[maxn],d[maxn];
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 N,i,j,a,b,k,t=0;

 while(scanf("%d",&N)!=EOF)
 {
  if(N==0) {printf("1\n");continue;}  //伤心啊，没考虑到这个特殊情况，让我错了好久，wa的好辛苦啊
  memset(d,0,sizeof(d));
  memset(father,0,sizeof(father));
  for(i=1;i<=maxn;i++)
  father[i]=i;
  t=0;
  for(i=1;i<=N;i++)
  {
   scanf("%d%d",&a,&b);
   if(t<a)
    t=a;
   if(t<b)
    t=b;
   
   if(find(a)!=find(b))
     merge(a,b);
  }
  for(i=1;i<=t;i++)
  {
   k=find(i);
   d[k]++;
   printf("%d %d\n",k,d[k]);
   
 } 
  a=d[1];
  for(i=2;i<=t;i++)
  if(d[i]>a)
  a=d[i];
  printf("%d\n",a);
}
  return 0;
}  
  
 // 2 4 1 4 3 1 5 3 6 7 7 8 100 3 20 100 100 2000 2000 100000