//#include <cmath>
#include <cstdio>
//------------------------------------------------------------
int  tcase;
int  icase;

int  S,T;
int  n,m,q;
int  i,j,k;
int  sx[500000];
int  sy[500000];

int  far[1000000];
int  num[510][510];
int  tab[510][510];

int  fa,fb;
//------------------------------------------------------------
int  getf(int d) { return far[d]==d ? d : far[d]=getf(far[d]); }
//------------------------------------------------------------
void link(int a,int b)
{
    //--0 init
    int  fa,fb;
    
    //--1 link
    if (a-1>=1&&!tab[a-1][b])
    {
        fa=getf(num[a-1][b]);
        fb=getf(num[a][b]);
        if (fa!=fb)
            far[fa]=fb;
    }
    if (a+1<=n&&!tab[a+1][b])
    {
        fa=getf(num[a+1][b]);
        fb=getf(num[a][b]);
        if (fa!=fb)
            far[fa]=fb;
    }
    if (b-1>=1&&!tab[a][b-1])
    {
        fa=getf(num[a][b-1]);
        fb=getf(num[a][b]);
        if (fa!=fb)
            far[fa]=fb;
    }
    if (b+1<=m&&!tab[a][b+1])
    {
        fa=getf(num[a][b+1]);
        fb=getf(num[a][b]);
        if (fa!=fb)
            far[fa]=fb;
    }

}
//------------------------------------------------------------
int  main( )
{
    for (scanf("%d",&tcase); ++icase<=tcase; )
    {
        //--0 init
        scanf("%d%d",&n,&m);
        far[S=0]=0;
        far[T=n*m+1]=n*m+1;
        for (i=1; i<=n; i++)
        for (j=1; j<=m; j++) num[i][j]=m*(i-1)+j; 
        for (i=1; i<=n; i++)
        for (j=1; j<=m; j++) far[num[i][j]]=num[i][j];
        
        //--1
        for (i=1; i<=n; i++)
        {
            scanf("\n");
            for (j=1; j<=m; j++) tab[i][j]=getchar()-'0';
        }
        
        //--2
        scanf("%d",&q);
        for (i=1; i<=q; i++)
        {
            scanf("%d%d",&sx[i],&sy[i]);
            tab[++sx[i]][++sy[i]]++;
        }
        
        //--3 link
        for (i=1; i<=n; i++)
        for (j=1; j<=m; j++)
        if (!tab[i][j]) link(i,j);
        
        for (i=1; i<=m; i++)
        {
            fa=getf(num[1][i]);
            fb=getf(S);
            if (fa!=fb)
                far[fa]=fb; 
            fa=getf(num[n][i]);
            fb=getf(T);
            if (fa!=fb)
                far[fa]=fb;
        }
        
        //--4 work
        fa=getf(S);
        fb=getf(T);
        if (fa==fb) printf("-1\n"); else
        {
            for (i=q; i>=1; i--)
            {
                if (!--tab[sx[i]][sy[i]])
                    link(sx[i],sy[i]);
                //=2 update
                fa=getf(S);
                fb=getf(T);
                if (fa==fb) break;
            }
            printf("%d\n",i);
        }
    }
}