#include <bits/stdc++.h>
using i64 = long long;


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, n * m));
	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 = [&](const std::pair<int, int> &pa, const std::pair<int, int> &pb) ->bool {
		return f[pa.first][pa.second] < f[pb.first][pb.second];
	};
	std::priority_queue<std::pair<int, int>, std::vector<std::pair<int, int>>, decltype(cmp)> pq(cmp);
	for(int i = 1; i <= k; ++i) {
		const auto &[x, y] = vec[i];
		v[x][y] = i;
		if(i == 1) {
			f[x][y] = 0;
			pq.emplace(x, y);
		}
	}
	while(!pq.empty()) {
		auto [x, y] = pq.top();
		pq.pop();
		for(auto [dx, dy] : std::vector<std::pair<int, int>>{{1, 0}, {-1, 0}, {0, 1}, {0, -1}}) {
			int xx = x + dx;
			int yy = y + dy;
			if(1 <= xx && xx <= n && 1 <= yy && yy <= m && v[xx][yy] != -1) {
				int val = f[x][y] + 1;
				if(v[xx][yy] >= 2) {
					val = std::max(val, k - v[xx][yy] + 1);
				}
				if(val < f[xx][yy]) {
					f[xx][yy] = val;
					pq.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] % (n * m);
			ans += 1ULL * f[i][j] * f[i][j];
		}
	}
	std::cout << ans << '\n';
	return 0;
}