#include<bits/stdc++.h>
#define LL long long
#define pII pair<int,int>
#define Fi first
#define Se second
#define pb push_back
using namespace std;
const int N=4e5+5;
const int Dx[8]={0,0,1,-1,1,1,-1,-1};
const int Dy[8]={1,-1,0,0,-1,1,-1,1};
int n,m,c,TOT,Sz[N],Fa[N];
LL V,E,R;
inline int Fd(int x)
{
	if(Fa[x]==x)return x;
	return Fd(Fa[x]);
}
unordered_map<LL,int>Ma,Nam;
vector<pII>St;
pII P[N];
inline bool In(int x,int y)
{
	return 1<=x&&x<=n&&1<=y&&y<=m;
}
inline int Num(int x,int y)
{
	if(!In(x,y)||x==n||y==m)return 0;
	if(Nam[x*m+y])return Nam[x*m+y];
	Nam[x*m+y]=++TOT,Fa[TOT]=TOT,Sz[TOT]=1;
	return TOT;
}
inline void Mrg(int x,int y,int op=0)
{
	x=Fd(x),y=Fd(y);
	if(x==y)return;
	if(Sz[x]<Sz[y])swap(x,y);
	if(op)St.pb({x,y});
	Fa[y]=x,Sz[x]+=Sz[y];
	R--;
}
inline void Work()
{
	scanf("%d%d%d",&n,&m,&c);
	TOT=0,Sz[0]=1,Fa[0]=0;
	St.clear(),Ma.clear(),Nam.clear();
	V=1ll*n*m,E=1ll*(n-1)*m+1ll*n*(m-1),R=1ll*(n-1)*(m-1)+1;
	for(int i=1,x,y;i<=c;i++)
	{
		scanf("%d%d",&x,&y);
		Ma[x*m+y]=1,V--;
		for(int j=0;j<4;j++)
		{
			int X=x+Dx[j],Y=y+Dy[j];
			if(In(X,Y)&&!Ma[X*m+Y])E--;
		}
		Mrg(Num(x-1,y),Num(x,y));
		Mrg(Num(x,y-1),Num(x,y));
		Mrg(Num(x-1,y-1),Num(x-1,y));
		P[i]={x,y};
	}
	if(V-E+R>2)return puts("0"),void();
	if(V<=2)return puts("-1"),void();
	if(n==1||m==1)return puts("1"),void();
	for(int i=1;i<=c;i++)
	{
		for(int j=0;j<8;j++)
		{
			int x=P[i].Fi+Dx[j],y=P[i].Se+Dy[j];
			if(!In(x,y)||Ma[x*m+y])continue;
			--V;
			LL E2=E;
			for(int j=0;j<4;j++)
			{
				int X=x+Dx[j],Y=y+Dy[j];
				if(In(X,Y)&&!Ma[X*m+Y])E--;
			}
			int Cnt=TOT;
			Mrg(Num(x-1,y),Num(x,y),1);
			Mrg(Num(x,y-1),Num(x,y),1);
			Mrg(Num(x-1,y-1),Num(x-1,y),1);
			if(V-E+R>2)return puts("1"),void();
			while(!St.empty())
			{
				pII t=St.back();St.pop_back();
				++R;
				Fa[t.Se]=t.Se,Sz[t.Fi]-=Sz[t.Se];
			}
			if(Num(x-1,y)>Cnt)Nam[(x-1)*m+y]=0;
			if(Num(x,y-1)>Cnt)Nam[x*m+y-1]=0;
			if(Num(x-1,y-1)>Cnt)Nam[(x-1)*m+y-1]=0;
			if(Num(x,y)>Cnt)Nam[x*m+y]=0;
			E=E2,V++,TOT=Cnt;
		}
	}
	puts("2");
}
int main()
{
	int T;scanf("%d",&T);
	while(T--){Work();}
}