#include <iostream>
using namespace std;
#include <set>
#include <algorithm>
#include <cmath>
#include <map>
#include <cstdio>
#include <string>
#include <cstring>
#include <string.h>
#include <stdlib.h>
#include <iomanip>
#include <fstream>
#include <stdio.h>
#include <stack>
#include <queue>
#include <ctype.h>
#include <vector>
#include <random>
#define ll long long
#define ull unsigned long long
#define pb push_back
#define rep(i, a, n) for (int i = a; i <= n; i++)
#define per(i, a, n) for (int i = n; i >= a; i--)
#define pii pair<int, int>
#define pli pair<ll, int>
#define pil pair<int, ll>
#define pll pair<ll ,ll > 
#define endl '\n'
const double pai = acos(-1);
ll extend_gcd(ll a, ll b, ll &x, ll &y)
{
    if (b == 0)
    {
        x = 1;
        y = 0;
        return a;
    }
    ll d = extend_gcd(b, a % b, y, x);
    y -= a / b * x;
    return d;
}
ll fastpow(ll a, ll n, ll mod)
{
    ll ans = 1;
    a %= mod;
    while (n)
    {
        if (n & 1)
            ans = (ans * a)%mod; //% mod
        a = (a * a)%mod;         //% mod
        n >>= 1;
    }
    return ans;
}
int dir[4][2] =
    {
        {0, 1}, {0, -1}, {1, 0}, {-1, 0}}; // d a w s

const int inf = 1000000000;
const ll mod = 1e9 + 7, P1 = 13331;
const double eps = 1e-7;
const int N =3000  + 10, M = 1e6 + 10;

int n,m,k;
bool vis[N][N];
ull ans[N][N];
string ss[N];

int a[N][N];

struct node
{
    int x,y,t,s;
    node(int a,int b,int c,int d)
    {
        x=a;
        y=b;
        t=c;
        s=d;
    }
    bool operator <(const node &b) const
    {
        return t>b.t;
    }
    // bool operator > (const node &b)const{
    //     return t>b.t;
    // }
};

int main()
{
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
  //  freopen("ain.txt", "r", stdin);freopen("aout.txt", "w", stdout);
    cin>>n>>m>>k;
    int xx,yy;
    rep(i,1,k)
    {
        int x,y;
        cin>>x>>y;
        if(i==1)
        {
            xx=x;
            yy=y;
        }
        a[x][y]=k-i+1;
    }
    rep(i,1,n)
    {
        cin>>ss[i];
        ss[i]=' '+ss[i];
    }
    rep(i,1,n)
    {
        rep(j,1,m)
        {
            ans[i][j]=inf;
        }
    }
    priority_queue<node> q;
    q.push(node(xx,yy,0,0));
    vis[xx][yy]=1;
    while(q.size())
    {
        //
        //cout<<111111;
        node u=q.top();
        q.pop();
        int x=u.x,y=u.y,t=u.t,s=u.s;
        ans[x][y]=min(ans[x][y],(ull)t);
       // cout<<"vis: "<<x<<' '<<y<<endl;
        
        rep(i,0,3)
        {
            int xx=x+dir[i][0],yy=y+dir[i][1];
            if(xx<1||xx>n||yy<1||yy>m||vis[xx][yy]||ss[xx][yy]=='#')
            {
                continue;
            }
            if(t+s+1>=a[xx][yy])//buhui
            {
                q.push(node(xx,yy,t+1,s));
                vis[xx][yy]=1;
                //
               // cout<<11111;
            }
            else
            {
                int temp=a[xx][yy]-(t+1+s);
                q.push(node(x,y,t+ temp  , s+temp ));
               // cout<<2222222;
            }

        }
    }
    ull anss=0;
    rep(i,1,n)
    {
        rep(j,1,m)
        {
            if(ans[i][j]==inf)
            {
                continue;
            }
            ull temp=ans[i][j]*ans[i][j];
            //
            //cout<<ans[i][j]<<" ";
            //
            anss+=temp;
        }
        //
       // cout<<endl;
        //
    }
    cout<<anss;
    return 0;
}