#include<iostream>
#include<cstring>
#include<stdio.h>
#include<queue>
using namespace std;
const int N = 3010;
const int K = 100005;
char a[N][N];
int shu[K], heng[K];
int n, m, k;
int f[N][N];
int rk[N][N];
typedef pair<int, int> pii;
queue<pii> q;
bool vis[N][N];
priority_queue<pii, vector<pii>, greater<pii>> hp;
int dx[5] = {0, 0, 0, -1, 1};
int dy[5] = {0, -1, 1, 0, 0};
int main(){
    scanf("%d%d%d", &n, &m, &k);
    for (int i = 1; i <= k;i++)
        scanf("%d %d", &heng[i], &shu[i]);
    for (int i = 1; i <= n;i++)
            scanf("%s ", a[i] + 1);
    memset(f, -1, sizeof f);
    for (int i = 2; i <= k;i++)
        a[heng[i]][shu[i]] = 'X', rk[heng[i]][shu[i]] = i;

    // for (int i = 1; i <= n;i++)
    // {
    //     for (int j = 1; j <= m;j++){
    //         cout << a[i][j];
    //     }
    //     cout << endl;
    // }

    f[heng[1]][shu[1]] = 0;
    q.push(pii(heng[1], shu[1]));
    while(!q.empty()){
        int x = q.front().first;
        int y = q.front().second;
        q.pop();
        for (int i = 1; i <= 4;i++){
            int nx = x + dx[i], ny = y + dy[i];
            if(nx<1||ny<1||nx>n||ny>m)
                continue;
            if(vis[nx][ny])
                continue;
            if(a[nx][ny]=='#')
                continue;
            else if(a[nx][ny]=='.'&&f[nx][ny]==-1){
                f[nx][ny] = f[x][y] + 1;
                q.push(pii(nx, ny));
            }
            else {
                if(!vis[nx][ny])
                hp.push(pii(max(f[x][y] + 1, k - rk[nx][ny] + 1), rk[nx][ny]));
            }
            vis[nx][ny] = true;
        }
        if(q.empty()&&!hp.empty()){
            int dis = hp.top().first, id = hp.top().second;
            hp.pop();
            f[heng[id]][shu[id]]=dis;
            q.push(pii(heng[id], shu[id]));
        }
        else {
            int tx = q.front().first, ty = q.front().second;
            if(!hp.empty()&&hp.top().first<=f[tx][ty]){
                int dis = hp.top().first, id = hp.top().second;
                f[heng[id]][shu[id]] = dis;
                q.push(pii(heng[id], shu[id]));
                hp.pop();
            }
        }
    }
    unsigned long long ans = 0;
    for (int i = 1; i <= n;i++)
        for (int j = 1; j <= m;j++){
            if(f[i][j]==-1)
                f[i][j] = 0;
            ans += 1ull*f[i][j] * f[i][j];
        }
    printf("%llu", ans);
}