#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<queue>
#include<algorithm>
#include<stack>
#include<cstring>
#include<vector>
#include<list>
#include<set>
#include<map>
using namespace std;
#define ll __int64
#define mod 1000000007
int scan()
{
    int res = 0 , ch ;
    while( !( ( ch = getchar() ) >= ‘0‘ && ch <= ‘9‘ ) )
    {
        if( ch == EOF )  return 1 << 30 ;
    }
    res = ch - ‘0‘ ;
    while( ( ch = getchar() ) >= ‘0‘ && ch <= ‘9‘ )
        res = res * 10 + ( ch - ‘0‘ ) ;
    return res ;
}
int l,k;
char a[510][510];
struct is
{
    int l,r;
}ch[250010];
int father[500010];
int vis[510][510];
int xz[4]={1,0,-1,0};
int yz[4]={0,1,0,-1};
int find_father(int x)
{
    return x==father[x]? x:father[x]=find_father(father[x]);
}
void hebing(int x,int y)
{
    int xx=find_father(x);
    int yy=find_father(y);
    if(xx!=yy)
    father[xx]=yy;
}
int number(int x,int y)
{
    return (x-1)*k+y;
}
int check(int ff)
{
    memset(vis,0,sizeof(vis));
    for(int i=0;i<=l*k;i++)
    father[i]=i;
    father[399999]=399999;
    father[400000]=400000;
    for(int i=1;i<=l;i++)
    for(int t=1;t<=k;t++)
    if(a[i][t]==‘1‘)
    vis[i][t]=1;
    else
    vis[i][t]=0;
    for(int i=1;i<=ff;i++)
    vis[ch[i].l+1][ch[i].r+1]=1;
    for(int i=1;i<=l;i++)
    for(int t=1;t<=k;t++)
    {
        if(vis[i][t])continue;
        for(int j=0;j<4;j++)
        {
            int xx=i+xz[j];
            int yy=t+yz[j];
            if(yy<=0||yy>k||vis[xx][yy])continue;
            if(xx==0)hebing(number(i,t),399999);
            else if(xx==l+1)hebing(number(i,t),400000);
            else hebing(number(i,t),number(xx,yy));
        }
    }
    int ans1=find_father(399999);
    int ans2=find_father(400000);
    if(ans1==ans2)
    return 1;
    return 0;
}
int main()
{
    int x,y,i,t;
    scanf("%d",&x);
    while(x--)
    {
        scanf("%d%d",&l,&k);
        for(i=1;i<=l;i++)
        scanf("%s",a[i]+1);
        scanf("%d",&y);
        for(t=1;t<=y;t++)
        scanf("%d%d",&ch[t].l,&ch[t].r);
        if(!check(0))
        {
            printf("-1\n");
            continue;
        }
        int st=1,en=y,mid;
        while(st<en)
        {
            mid=(st+en)>>1;
            if(check(mid))
            st=mid+1;
            else
            en=mid;
        }
        printf("%d\n",st);
    }
    return 0;
}