//#include<iostream>

 #include<cstring>

 #include<cstdio>

 //#include<math.h>

 //#include<set>

 //#include<queue>

 //#include<bitset>

 //#include<vector>

 #include<algorithm>

 #include<stdlib.h>

 using namespace std;

 #define LL long long

 int qread()

 {

     char c; int s=,f=; while ((c=getchar())<'' || c>'') (c=='-') && (f=-);

     do s=s*+c-''; while ((c=getchar())>='' && c<=''); return s*f;

 }

 //Pay attention to '-' , LL and double of qread!!!!

 int T,n,m,c;

 #define maxn 2400011

 #define maxm 10000011

 int Abs(int x) {return x>?x:-x;}

 struct Poi

 {

     int x,y,id;

     bool operator == (const Poi &b) const {return x==b.x && y==b.y;}

 }cc[maxn];

 bool cmpx(const Poi &a,const Poi &b) {return a.x<b.x || (a.x==b.x && a.y<b.y);}

 bool cmpy(const Poi &a,const Poi &b) {return a.y<b.y || (a.y==b.y && a.x<b.x);}

 int px[maxn],py[maxn],lx,ly;

 #define maxh 1000007

 struct Hash

 {

     struct Edge{int to,x,y,next;}edge[maxn]; int first[maxh],le;

     void clear() {memset(first,,sizeof(first)); le=;}

     int geth(int x,int y) {return (x*1000000000ll+y)%maxh;}

     void in(int x,int y,int id)

     {int h=geth(x,y); Edge &e=edge[le]; e.to=id; e.x=x; e.y=y; e.next=first[h]; first[h]=le++;}

     void insert(int x,int y,int id) {if (!~find(x,y)) in(x,y,id);}

     int find(int x,int y)

     {

         int h=geth(x,y);

         for (int i=first[h];i;i=edge[i].next) if (edge[i].x==x && edge[i].y==y) return edge[i].to;

         return -;

     }

 }h,hh;

 const int dx[]={-,,,-,,-,,},

 dy[]={-,-,-,,,,,},

 ddx[]={-,,,},ddy[]={,,-,};

 int TOT,ANS,dfn[maxn],Time,low[maxn],top; Poi sta[maxn];

 struct Edge{int to,next;}edge[maxm]; int first[maxn],le=;

 void in(int x,int y) {Edge &e=edge[le]; e.to=y; e.next=first[x]; first[x]=le++;}

 void insert(int x,int y) {in(x,y); in(y,x);}

 void tarjan(int id,int fa)

 {

     TOT++;

     int son=;

     dfn[id]=low[id]=++Time;

     for (int i=first[id];i;i=edge[i].next)

     {

         Edge &e=edge[i]; int u=e.to;

         if (!dfn[u])

         {

             sta[++top]=(Poi){id,u,};

             son++;

             tarjan(u,id);

             low[id]=min(low[id],low[u]);

             if (low[u]>=dfn[id])

             {

 //                cout<<id<<' '<<u<<endl;

                 if (fa) ANS=;

                 while (sta[top].x!=id || sta[top].y!=u) top--;

                 top--;

             }

         }

         else if (u!=fa && dfn[u]<dfn[id])

         {

             sta[++top]=(Poi){id,u,};

             low[id]=min(low[id],dfn[u]);

         }

     }

     if (fa== && son>) ANS=;

 }

 int main()

 {

     T=qread();

     while (T--)

     {

         n=qread(); m=qread(); c=qread();

         for (int i=;i<=c;i++) {cc[i].x=qread(); cc[i].y=qread();}

         if (1ll*n*m-c<) puts("-1");

         else if (1ll*n*m-c==)

         {

             if (c==) {puts("-1"); continue;}

             sort(cc+,cc++c,cmpx);

             int x1=,x2=,y1,y2;

             for (int x=,y=,i=;i<=c;i++,x+=(y==m),y=y==m?:y+)

             {

                 if (cc[i].x!=x || cc[i].y!=y)

                 {

                     if (!x1) x1=x,y1=y;

                     else x2=x,y2=y;

                     i--;

                 }

             }

             if (x1==) {x1=n; y1=m-; x2=n; y2=m;}

             else if (x2==) {x2=n; y2=m;}

             if (Abs(x1-x2)+Abs(y1-y2)==) puts("-1");

             else puts("");

         }

         else

         {

             if (c==)

             {

                 if (n== || m==) puts("");

                 else puts("");

                 continue;

             }

             int tc=c;

             for (int i=;i<=c;i++) cc[i].id=;

             lx=ly=;

             hh.clear();

             for (int i=;i<=c;i++) hh.insert(cc[i].x,cc[i].y,i);

             for (int i=,tmp=c;i<=tmp;i++)

             {

                 px[++lx]=cc[i].x; py[++ly]=cc[i].y;

                 for (int j=;j<;j++)

                 {

                     int xx=dx[j]+cc[i].x,yy=dy[j]+cc[i].y;

                     if (xx<= || xx>n || yy<= || yy>m || ~hh.find(xx,yy)) continue;

                     c++; cc[c].x=xx; cc[c].y=yy; cc[c].id=cc[c-].id+; hh.insert(xx,yy,);

                     px[++lx]=xx; py[++ly]=yy;

                 }

             }

             px[++lx]=; px[++lx]=n; sort(px+,px++lx); lx=unique(px+,px++lx)-px-;

             py[++ly]=; py[++ly]=m; sort(py+,py++ly); ly=unique(py+,py++ly)-py-;

             for (int i=;i<=c;i++) cc[i].x=lower_bound(px+,px++lx,cc[i].x)-px,

             cc[i].y=lower_bound(py+,py++ly,cc[i].y)-py;

             hh.clear(); for (int i=;i<=c;i++) hh.insert(cc[i].x,cc[i].y,cc[i].id);

             for (int i=;i<=ly;i++) if (!~hh.find(,i))

             {cc[c+]=(Poi){,i,cc[c].id+}; c++; hh.insert(cc[c].x,cc[c].y,cc[c].id);}

             for (int i=;i<=ly;i++) if (!~hh.find(lx,i))

             {cc[c+]=(Poi){lx,i,cc[c].id+}; c++; hh.insert(cc[c].x,cc[c].y,cc[c].id);}

             for (int i=;i<=lx;i++) if (!~hh.find(i,))

             {cc[c+]=(Poi){i,,cc[c].id+}; c++; hh.insert(cc[c].x,cc[c].y,cc[c].id);}

             for (int i=;i<=lx;i++) if (!~hh.find(i,ly))

             {cc[c+]=(Poi){i,ly,cc[c].id+}; c++; hh.insert(cc[c].x,cc[c].y,cc[c].id);}

             memset(first,,sizeof(first)); le=;

             sort(cc+,cc++c,cmpx);

             for (int i=;i<c;i++) if (cc[i].id && cc[i+].id && cc[i].x==cc[i+].x) insert(cc[i].id,cc[i+].id);

             sort(cc+,cc++c,cmpy);

             for (int i=;i<c;i++) if (cc[i].id && cc[i+].id && cc[i].y==cc[i+].y) insert(cc[i].id,cc[i+].id);

             TOT=ANS=Time=top=;

             memset(dfn,,sizeof(dfn));

             tarjan(,);

             if (TOT<c-tc) puts("");

             else if ((n== || m==) && (n*m>TOT)) puts("");

             else if (ANS) puts(""); else puts("");

         }

     }

     return ;

 }