#include <bits/stdc++.h>
using namespace std;
struct Point {
	int x, y;
	Point(int x = 0, int y = 0) : x(x), y(y) {}
} a[100005];
bool vis[3005][3005], flag[3005][3005];
char c[3005][3005];
int dir[4][2] = {1, 0, -1, 0, 0, -1, 0, 1};
int n, m, K;
int main() {
	scanf("%d%d%d", &n, &m, &K);
	for (int i = 1; i <= K; ++i) {
		scanf("%d%d", &a[i].x, &a[i].y);
		flag[a[i].x][a[i].y] = 1;
	}
	for (int i = 1; i <= n; ++i)
		scanf("%s", c[i] + 1);
	queue<Point> q;
	vis[a[1].x][a[1].y] = 1;
	unsigned long long step = 0;
	unsigned long long ans = 0;
	for (step = 1; step <= 2 * n * m; ++step) {
		if (step <= K) {
			flag[a[K - step + 1].x][a[K - step + 1].y] = 0;
			q.push(a[1]);
		}
		int sz = q.size();
		for (int i = 1; i <= sz; ++i) {
			auto tmp = q.front();
			q.pop();
			int x = tmp.x, y = tmp.y;
			for (int j = 0; j < 4; ++j) {
				int nx = x + dir[j][0], ny = y + dir[j][1];
				if (nx >= 1 && nx <= n && ny >= 1 && ny <= m &&
					!vis[nx][ny] && c[nx][ny] == '.' && !flag[nx][ny]) {

					vis[nx][ny] = 1;
					q.push(Point{nx, ny});
					ans = ans + step * step;
				}
			}
		}
	}
	cout << ans << endl;
	return 0;
}