#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
using namespace std;
typedef unsigned long long ll;
const int mod = 1e9 + 7;
const int N = 3e3 + 5;
int dx[4] = {0, -1, 0, 1};
int dy[4] = {1, 0, -1, 0};

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	int n, m, k; cin >> n >> m >> k;
	vector<pair<int, int>> a(k);
	vector<vector<int>> ans(n, vector<int>(m, mod)), vis(n, vector<int>(m, 0));
	for (int i = 0; i < k; i++) {
		cin >> a[i].first >> a[i].second;
		a[i].first--;
		a[i].second--;
		vis[a[i].first][a[i].second] = i;
	}
	for (int i = 0; i < n; i++) {
		string s; cin >> s;
		for (int j = 0; j < m; j++)
			if (s[j] == '#')
				vis[i][j] = -1;
	}
	ans[a[0].first][a[0].second] = 0;
	priority_queue<pair<int, pair<int, int>>> q;
	auto upd = [&](auto p, int d) {
		for (int i = 0; i < 4; i++) {
			int nx = p.first + dx[i];
			int ny = p.second + dy[i];
			if (nx < 0 || ny < 0 || n <= nx || m <= ny || vis[nx][ny] == -1)
				continue;
			if ((vis[nx][ny] + d + 1 >= k || vis[nx][ny] == 0) && ans[nx][ny] > d + 1) {
				ans[nx][ny] = d + 1;
				q.push(make_pair(-d - 1, make_pair(nx, ny)));
			}
		}
	};
	q.push(make_pair(0, a[0]));
	int lo = 0;
	ll res = 0;
	while (!q.empty()) {
		auto [d, p] = q.top();
		q.pop();
		d = -d;
		if (p != a[0] && d != ans[p.first][p.second])
			continue;
		if (p != a[0])
			res += (ll)d * (ll)d;
		else if (d == lo && lo + 1 < k)
			q.push(make_pair(-(++lo), a[0]));
		upd(p, d);
	}

	cout << res << "\n";
}