#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
#define pii pair<int, int>
void solve();

signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int T = 1;
	//cin >> T;
	while (T--)solve();
	return 0;
}
const int mod = 998244353;
#define ull unsigned long long
void solve() {
	int n, m, k;
	cin >> n >> m >> k;
	vector<int>t(k + 1);
	vector<int>v(n * m);
	auto get = [&](int x, int y)->int {
		return x * m + y;
	};
	vector<ull>ans(n * m,1e10);
	vector<int>add(k + 1,-1);
	queue<pii>q;
	vector<bool>vis(n * m);
	//return;
	for (int i = 1; i <= k; i++) {
		int x, y;
		cin >> x >> y;
		x--;
		y--;
		int j = get(x, y);
		v[j] = k - i + 1;
		if (i == 1) {
			q.push({ 0,j });
			vis[j] = 1;
		}
	}
	vector<string>s(n);
	for (int i = 0; i < n; i++) {
		cin >> s[i];
		for (int j = 0; j < m; j++) {
			if (s[i][j] == '#') {
				vis[get(i, j)] = 1;
			}
		}
	}
	vector<int>dx = { -1,1,0,0 };
	vector<int>dy = { 0,0,-1,1 };
	//return;
	while (q.size()) {
		pii it = q.front();
		q.pop();
		int u = it.second, id = it.first;
		if (id<=k&&add[id] != -1) {
			q.push({ id + 1,add[id] });
			add[id] = -1;
		}
		ans[u] = min(ans[u], (ull)id);
		int x = u / m, y = u % m;
		for (int t = 0; t < 4; t++) {
			int nx = dx[t] + x, ny = dy[t] + y;
			int j = get(nx, ny);
			if ( nx < 0 || nx >= n || ny < 0 || ny >= m||vis[j] == 1 )continue;
			if (v[j] > id + 1) {
				add[v[j] - 1] = j;
			}
			else {
				vis[j] = 1;
				q.push({ id + 1,j });
			}
		}
	}
	ull co = 0;
	for (int i = 0; i < n * m; i++) {
		if (ans[i] != 1e10) {
			co += ans[i] * ans[i];
		}
	}
	cout << co << endl;
}