#include <bits/stdc++.h>
using i64 = long long;
constexpr int INF = 1E9;

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int n, m, k;
	std::cin >> n >> m >> k;
	std::vector<std::vector<int>> v(n + 1, std::vector<int>(m + 1));
	std::vector<std::vector<int>> f(n + 1, std::vector<int>(m + 1, INF));
	std::vector<std::pair<int, int>> vec(k + 1);
	for(int i = 1; i <= k; ++i) {
		auto &[x, y] = vec[i]; 
		std::cin >> x >> y;
	}
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			char ch;
			std::cin >> ch;
			v[i][j] = -1 * (ch == '#');
		}
	}
	auto cmp = [&f](const std::pair<int, int> &pa, const std::pair<int, int> &pb) {
		return f[pa.first][pa.second] > f[pb.first][pb.second];
	};
	std::queue<std::pair<int, int>> q;
	std::priority_queue<std::pair<int, int>> tq;
	for(int i = 1; i <= k; ++i) {
		const auto &[x, y] = vec[i];
		v[x][y] = i;
		if(i == 1) {
			f[x][y] = 0;
			q.emplace(x, y);
		}
	}
	while(!q.empty() || !tq.empty()) {
		std::pair<int, int> t;
		if(q.empty() || (!tq.empty() && cmp(q.front(), tq.top()))) {
			t = tq.top();
			tq.pop();
		} else {
			t = q.front();
			q.pop();
		}
		const auto &[x, y] = t;
		for(const auto &[dx, dy] : std::vector<std::pair<int, int>>{{1, 0}, {-1, 0}, {0, 1}, {0, -1}}) {
			int xx = x + dx, yy = y + dy;
			if(1 <= xx && xx <= n && 1 <= yy && yy <= m && v[xx][yy] != -1 && f[xx][yy] == INF) {
				if(v[xx][yy] >= 2) {
					f[xx][yy] = std::max(f[x][y] + 1, k - v[xx][yy] + 1);
					tq.emplace(xx, yy);
				} else {
					f[xx][yy] = f[x][y] + 1;
					q.emplace(xx, yy);
				}
			}
		}
	}
	unsigned long long ans = 0;
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			f[i][j] = (f[i][j] == INF ? 0 : f[i][j]);
			ans += 1ULL * f[i][j] * f[i][j];
		}
	}
	std::cout << ans << '\n';
	return 0;
}