OJ Board

can anyone pl tell me why i'm getting WA with this code
#include<stdio.h>
int main()
{
int n,i,j,p,q,temp,k=0;
char a[1000002];


while(fgets(a,1000001,stdin))
{
fflush(stdin);
if(a[0]=='\n')
break;
scanf("%d",&n);
k++;
printf("Case %d:\n",k);
for(i=0;i<n;i++)
{
scanf("%d %d",&p,&q ...