#include <bits/stdc++.h>

constexpr int ds[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};

void solve() 
{
    int n, m, k;
    std::cin >> n >> m >> k;
    std::vector<std::pair<int, int>> a(k);
    for (auto &[x, y] : a) {
        std::cin >> x >> y;
        x--, y--;
    }
    std::vector<std::string> s(n);
    for (int i = 0; i < n; ++i) {
        std::cin >> s[i];
    } 
    int cnt = 1;
    std::vector ans(n, std::vector<int>(m));
    for (const auto &[x, y] : a) {
        ans[x][y] = -cnt;
        cnt++;
    }
    std::queue<std::pair<int, int>> q, tq;
    ans[a[0].first][a[0].second] = 1;
    q.emplace(a[0]);
    while (!q.empty() || !tq.empty()) {
        int x, y;
        if (!q.empty()) {
            if (!tq.empty()) {
                auto [t1, t2] = q.front();
                auto [t3, t4] = tq.front();
                if (ans[t1][t2] < ans[t3][t4]) {
                    x = t1;
                    y = t2;
                    q.pop();
                } else {
                    x = t3;
                    y = t4;
                    tq.pop();
                }
            } else {
                auto [tx, ty] = q.front();
                x = tx;
                y = ty;
                q.pop();
            }
        } else {
            auto [tx, ty] = tq.front();
            x = tx;
            y = ty;
            tq.pop();
        }
        for (int i = 0; i < 4; ++i) {
            int nx = x + ds[i][0];
            int ny = y + ds[i][1];
            if (nx >= n || nx < 0 || ny >= m || ny < 0) continue;
            if (s[nx][ny] == '#') continue;
            if (ans[nx][ny] == 0) {
                ans[nx][ny] = ans[x][y] + 1;
                q.emplace(nx, ny);
            }
            if (ans[nx][ny] < 0) {
                ans[nx][ny] = std::max(k + ans[nx][ny] + 2, ans[x][y] + 1);
                tq.emplace(nx, ny);
            }
        }
    }
    uint64_t sum = 0;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            if (ans[i][j] > 0) ans[i][j]--;
            else ans[i][j] = 0;
            sum = sum + (uint64_t)ans[i][j] * (uint64_t)ans[i][j];
            // std::cout << ans[i][j] << " \n"[j == m - 1];
        }
    }
    std::cout << sum << '\n';
}

int main() 
{
    std::cin.tie(nullptr)->std::ios::sync_with_stdio(false);
    
    int t = 1;
    while(t--) {
        solve();
    }
    
    return 0;
}