#include<stdio.h>

#include<iostream>

#include<stack>

#include<queue>

#include<math.h>

#include<stdlib.h>

#include<cstring>

using namespace std;

#define Max(a,b) (a>b?a:b)

#define Min(a,b) (a<b?a:b)

#define INF 0xfffffff

#define maxn 110

struct Point

{

    int x, y, step;

}B[maxn];

char maps[maxn][maxn];

bool vis[maxn][maxn];

int dir[][] = { {-,-},{-,},{,-},{,},{-,},{,},{,-},{,}};

int n, m, k;

bool OK(Point P,int i,int End)

{

    if(P.x >=  && P.x < n && P.y >=  && P.y < m && maps[P.x][P.y] != '#' && maps[P.x][P.y] <= End+''  && !vis[P.x][P.y])

    {

        if(i < )

        {

            if(i ==  && maps[P.x+][P.y] == '#' && maps[P.x][P.y+] == '#')

                return false;

            if(i ==  && maps[P.x+][P.y] == '#' && maps[P.x][P.y-] == '#')

                return false;

            if(i ==  && maps[P.x-][P.y] == '#' && maps[P.x][P.y+] == '#')

                return false;

            if(i ==  && maps[P.x-][P.y] == '#' && maps[P.x][P.y-] == '#')

                return false;

        }

        return true;

    }

    return false;

}

int BFS(int Star,int End)

{

    Point P, Pn;

    queue<Point> Q;

    memset(vis, false, sizeof(vis));

    Q.push(B[Star]);

    if(B[End].x == B[].x && B[End].y == B[].y && End != )

        return -;

    while( !Q.empty() )

    {

        P = Q.front();

        Q.pop();

        if(P.x == B[End].x && P.y == B[End].y)

            return P.step;

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

        {

            Pn.x = P.x + dir[i][];

            Pn.y = P.y + dir[i][];

            Pn.step = P.step + ;

            if( OK(Pn,i, End) )

            {

                vis[Pn.x][Pn.y] = true;

                Q.push(Pn);

            }

        }

    }

    return -;

}

int main()

{

    int T, i;

    cin >> T;

    while(T--)

    {

        cin >> n >> m >> k;

        for(i=; i<n; i++)

            scanf("%s", maps[i]);

        for(i=; i<=k; i++)

        {

            cin >> B[i].x >> B[i].y;

            B[i].x --, B[i].y --;

            B[i].step = ;

            maps[B[i].x][B[i].y] = i + '';

        }

        int ans, sum;

        ans = sum = ;

        for(i=; i<k; i++)

        {

            ans = BFS(i, i+);

            if(ans == -)

                break;

            sum += ans;

        }

        if( k == i)

            printf("%d\n", sum);

        else

            printf("-1\n");

    }

    return ;

}

/*

3

3 3 2

...

#..

...

1 1

1 2

1 1

答案 -1

*/