#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e3 + 5;

int mp[N][N];
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
int vis[N][N];
int res[N][N];

struct node
{
    ll x, y, step;
    bool operator<(const node &a) const
    {
        return step > a.step;
    }
};

void solve()
{
    int n, m, k;
    cin >> n >> m >> k;

    priority_queue<node> q;
    for (int i = 1; i <= k; i++)
    {
        int a, b;
        cin >> a >> b;
        mp[a][b] = k - i + 1;

        if (i == 1)
            q.push({a, b, 0});
    }

    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
        {
            char ch;
            cin >> ch;
            if (ch == '#')
                mp[i][j] = -1;
        }
    }

    unsigned long long ans = 0;

    while (!q.empty())
    {
        auto [x, y, step] = q.top();
        q.pop();

        if (vis[x][y])
            continue;
        vis[x][y] = 1;

        ans += step * step;
        res[x][y] = step * step;

        for (int k = 0; k < 4; k++)
        {
            int nx = x + dx[k];
            int ny = y + dy[k];

            if (nx < 1 || nx > n || ny < 1 || ny > m || mp[nx][ny] == -1 || vis[nx][ny])
                continue;

            q.push({nx, ny, max(step + 1, 1LL * mp[nx][ny])});
        }
    }

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

    cout << ans << endl;
}

int main()
{
    cin.tie(0)->ios::sync_with_stdio(false);

    int t = 1;
    // cin >> t;
    while (t--)
        solve();

    return 0;
}