#include <iostream>
#include <limits>
#include <queue>
#define int long long

using namespace std;

constexpr const int inf = numeric_limits<int>::max();

int n, m, k;
bool grid[3001][3001];
int snake_pos[3001][3001];
int dist[3001][3001];
pair<int, int> snake[100001];

struct node
{
    int x, y, d;
    node(int x, int y, int d) : x(x), y(y), d(d)
    {
    }
};

void bfs()
{
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            dist[i][j] = inf;
        }
    }

    int dx[] = {0, 0, 1, -1};
    int dy[] = {1, -1, 0, 0};

    queue<node> q;
    int current_idle_d = 0;
    q.push(node(snake[0].first, snake[0].second, 0));
    dist[snake[0].first][snake[0].second] = 0;
    while (!q.empty())
    {
        node cur = q.front();
        q.pop();
        if (cur.d > current_idle_d)
        {
            current_idle_d = cur.d;
            q.push(node(snake[0].first, snake[0].second, cur.d));
        }

        // left, right, up, down
        for (int i = 0; i < 4; i++)
        {
            int new_x = cur.x + dx[i];
            int new_y = cur.y + dy[i];
            int new_d = cur.d + 1;
            if (new_x < 0 || new_x >= n)
                continue;
            if (new_y < 0 || new_y >= m)
                continue;
            if (dist[new_x][new_y] != inf)
                continue;
            if (grid[new_x][new_y])
                continue;

            if (snake_pos[new_x][new_y] != -1)
            {
                if (snake_pos[new_x][new_y] > new_d)
                    continue;
            }

            dist[new_x][new_y] = min(new_d, dist[new_x][new_y]);
            q.push(node(new_x, new_y, new_d));
        }
    }
}

int32_t main()
{
    cin >> n >> m >> k;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            snake_pos[i][j] = -1;
        }
    }
    for (int i = 0; i < k; i++)
    {
        int x, y;
        cin >> x >> y;
        snake[i] = {x - 1, y - 1};
        snake_pos[x - 1][y - 1] = k - i;
    }
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            char c;
            cin >> c;
            grid[i][j] = (c == '#');
        }
    }
    bfs();

    unsigned int ans = 0;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            if (dist[i][j] == inf)
                continue;
            ans += dist[i][j] * dist[i][j];
            // cout << dist[i][j] << ' ';
        }
        // cout << endl;
    }
    cout << ans << endl;
    return 0;
}