#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<algorithm>
#define LL long long
using namespace std;
const int N=5005;
int read()
{
	int x=0,f=1;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
	while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
	return x*f;
}
int r,c,n,frog[N][N],vis[N][N],res=2;
struct Node{int x,y;}dot[N];
bool cmp(Node o1,Node o2){return (o1.x==o2.x)?(o1.y<o2.y):(o1.x<o2.x);}
bool in(int x,int y){return x>=1&&x<=r&&y>=1&&y<=c;}
int main()
{
	r=read(),c=read(),n=read();
	for(int i=1;i<=n;i++)
	{
		dot[i].x=read(),dot[i].y=read();
		frog[dot[i].x][dot[i].y]=1;
	}
	sort(dot+1,dot+1+n,cmp);
	for(int i=1;i<=n;i++)
	{
		for(int j=i+1;j<=n;j++)
		{
			if(vis[dot[j].x][dot[j].y]==i)continue;
			vis[dot[j].x][dot[j].y]=i;
			int dx=dot[j].x-dot[i].x,dy=dot[j].y-dot[i].y;
			int tx=dot[i].x-dx,ty=dot[i].y-dy;
			if(in(tx,ty))continue;
			if(!in(dot[i].x+(res-1)*dx,dot[i].y+(res-1)*dy))continue;
			tx=dot[j].x,ty=dot[j].y;
			int num=1;
			while(in(tx,ty))
			{
				num++;
				if(!frog[tx][ty]){num=0;break;}
				tx+=dx,ty+=dy;
			}
			res=max(res,num);
		}
	}
	printf("%d\n",res<3?0:res);
	return 0;
}

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<algorithm>
#define LL long long
#define INF 0x3f3f3f3f
using namespace std;
const int N=5005;
int read()
{
	int x=0,f=1;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
	while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
	return x*f;
}
LL x[N],y[N];
int f[1000005];
LL p(LL a){return a*a;}
int main()
{
	int T=read();
	while(T--)
	{
		memset(f,0x3f,sizeof(f));
		int n=read();
		for(int i=1;i<=n;i++)x[i]=read(),y[i]=read();
		f[x[1]]=0;
		for(int i=2;i<=n;i++)
		{
			int d=sqrt(p(y[i])-p(y[i]-y[1]));
			for(int j=1;j<=d;j++)
			{
				if(x[i]-j<x[1])continue;
				if(x[i]+j>x[n])f[x[n]]=min(f[x[i]-j]+1,f[x[n]]);
				else f[x[i]+j]=min(f[x[i]-j]+1,f[x[i]+j]);
			}
		}
		printf("%d\n",f[x[n]]==INF?-1:f[x[n]]);
	}
	return 0;
}