#include <bits/stdc++.h>
using namespace std;
int dir[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
void solve()
{
    int n, m, k;
    cin >> n >> m >> k;
    const int INF = 1e9;
    vector dis(n, vector<int>(m, INF));
    vector to_back(n, vector<int>(m, 0)), vis(n, vector<int>(m, 0));
    vector<string> g(n);
    auto check = [&](int x, int y)
    {
        return x >= 0 && x < n && y >= 0 && y < m && g[x][y] != '#';
    };
    using P = pair<int, int>;
    vector<P> snake(k);
    for (int i = 0; i < k; i++)
    {
        auto &[x, y] = snake[i];
        cin >> x >> y;
        x--, y--;
        to_back[x][y] = k - 1 - i;
    }
    using T = array<int, 3>;
    priority_queue<T> p;
    queue<T> q;
    for (auto &s : g)
        cin >> s;

    q.push(T({0,snake[0].first, snake[0].second}));
    dis[snake[0].first][snake[0].second] = 0;
    while (!q.empty())
    {
        auto [ta, xa, ya] = q.front();
        int x = xa,y = ya,t = ta;
        if (!p.empty())
        {
            auto [tb,xb,yb] = p.top();
            tb = -tb;
            if (tb < ta)
            {
                x = xb,y = yb,t = tb;
                p.pop();
            }
            else
            {
                q.pop();
            }
        }
        else
            q.pop();
        if (vis[x][y])
            continue;
        vis[x][y] = 1;
        for (int i = 0; i < 4; i++)
        {
            auto [nx, ny] = P(x + dir[i][0], y + dir[i][1]);
            if (!check(nx, ny) || vis[nx][ny])
                continue;
            if (to_back[nx][ny])
            {
                dis[nx][ny] = min(dis[nx][ny], t + 1 + max(0,to_back[nx][ny] - dis[x][y]));
                p.push(T({-dis[nx][ny],nx,ny}));
            }
            else
            {
                dis[nx][ny] = min(dis[nx][ny], t + 1);
                q.push(T({dis[nx][ny], nx, ny}));
            }
        }
    }
    uint64_t res = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
        {
            if (dis[i][j] == INF)
                continue;
            res += 1ull * dis[i][j] * dis[i][j];
        }
    cout << res << '\n';
}

int main()
{
#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
    auto t = clock();
#endif
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
#ifdef LOCAL
    cerr << clock() - t << '\n';
#endif
    return 0;
}